Welcome to my Nami guide!
Nami is my favorite champion in League of Legends. I feel her kit makes her possibly the best Support in the game at this point in time and I have also branched out in discovering other fun ways to use her outside of Support role. So if you're bored and looking for a fun time play some Normal matches and try the other builds out! Perhaps you'll be washed away by how good Nami really is. ;)

Some quick notes...

Skill casting.. self casting

• A quick way to cast your W Ebb and Flow and your E Tidecaller's Blessing on yourself is to hold the Alt key and then press the skill key.

Aqua Prison use..

• Cast the skill from areas where players can't see you, players will not be able to dodge it if they don't know it's coming.
• Use your Tidecaller's Blessing to slow enemies before casting your Aqua Prison. It becomes much harder to dodge when you're unable to move quickly.
• Observe your enemies movements at times when you miss or they attempt to dodge. For example if a player moves backwards in an attempt to dodge your Aqua Prison next time aim it farther backwards.
• Know your enemies. If an opposing player is using a champion with a gap closer such as Akali or Jax refrain from toss your Aqua Prison until after they leap at you and then toss it at yourself. This way the ability hits both them and you, they go bobbing into the air and you gain a +40 movement speed boost.

I'll first cover a decent method to jungling with Nami. While definitely not the best choice for a jungle, if you're looking for a good time in a Normal queue or are playing a Custom match with some friends playing jungle with Nami can be a fun way to mix things up.

To start off, you'll need Smite as your first Summoner Spell. The best choice for the second one would be Flash since you do not have any type of gap closer in your kit. ( Surging Tides is not really good enough to be considered one). You could get Ghost or Teleport but I'd highly recommend the first two. Next we'll move on to Masteries and Runes.

Mastery notes...

Fury , Deadliness , and Weapon Expertise in the Offense Tree will help give you a little extra damage and it goes well with the Armor Pen / Attack Speed / Attack Damage runes. As a Nami jungle you will need all the damage you can get seeing as your only real damage against jungle monsters outside of your auto attack is your Aqua Prison which has a painful cool time early on.

I would recommend taking Durability / Tough Skin / Veteran's Scars in the Defense Tree. Hardiness and Resistance were really just fillers to make the Veteran's Scars available however they will add a small amount more tankiness to make your jungling expedition more comfortable earlier in the game.

In the Utility Tree I really believe you need the Runic Affinity . Nami uses large portions of mana rather quickly and early on has decent length cool times so the longer you can hold the blue buff the better. Also seeing that you will lack damage until you can get some items having the red buff a little longer doesn't hurt either. Summoner's Insight and Mastermind will help reduce the cool time on your Smite. Improved Recall I used mainly as a filler, I suppose you could possibly put another point in Wanderer or Expanded Mind if you preferred a little more move speed or mana.

Rune Notes...

I tried out many different kinds of runes when I started experimenting with the idea of Jungle Nami and I find that a good balance of Armor Pen / Magic Pen, Armor, Magic Resist, Attack Speed, Damage, and Ability Power runes works the best. Late game you will be more reliant on items to make or break your game play but early on the small amount of added damage and ability power helps make a large difference. I also included some gold runes for an extra 6g or so every minute.

Marks:
Greater Mark of Hybrid Penetration x3
Greater Mark of Armor x3
Greater Mark of Attack Speed x3

Seals:
Greater Seal of Armor x5
Greater Seal of Gold x4

Glyphs:
Greater Glyph of Magic Resist x3
Greater Glyph of Ability Power x6

Quints:
Greater Quintessence of Attack Damage x3

Clearing Jungle Camps

In order to get off to a good foot, start off with your Q Aqua Prison and get a leash at the Blue Golem. After killing the Golem and its creeps you should be level 2, put a point on E Tidecaller's Blessing and then position yourself in front of the Wolves against the wall located in front of them. Q Aqua Prison the group of Wolves then use the E Tidecaller's Blessing on yourself and kill off the two smaller wolves (you should be able to kill them with 1 hit each using your Tidecaller's Blessing). The Large Wolf will take slightly longer to kill but finishing off the two smaller ones before they hit you will save you some health. After killing the Blue Golem and the group of Wolves use a Health Potion to heal yourself (or two if needed) and head over to the Wraiths and repeat the same strategy. Use your Aqua Prison on the Wraiths and then cast your Tidecaller's Blessing on yourself and kill off the smaller wraiths.

Upon killing the Wraiths use Health Potion to heal yourself and head over to the Red Lizard camp to get the Red Buff from him. Be sure to use the same skill order in this camp as all the others. After killing the Red Lizard Elder and obtaining the Red Buff you should have reached level 3. Put your skill point on W Ebb and Flow then heal yourself up, you're now ready to gank!

Assisting your team members / Ganking

By now you've done what everyone calls 'the impossible' when it comes to Nami jungling. You have cleared your camps just as fast as any other jungle could, have both buffs, and are now ready to gank with both a decent amount of HP and Mana. Where you go from here is very situational however after clearing red you are in a good spot to gank the Mid Lane. While clearing the jungle for the first 3 levels it's a good idea to keep an eye on Top/Mid lanes to see how they are fairing against the opposing teams players. If both lanes are pushing fairly well choose one and help try to push the turret. This will create a lot of pressure on the other teams jungle because he will have two lanes to help but he can only be at one location at a time. However if either of your Top/Mid are struggling assist them to ensure they won't lose the lane.

Fighting other players, how to land the perfect gank!

Nami's Q Aqua Prison takes a very long time to master. It requires both good timing and aiming as well as predicting how the opposing player(s) will move. However there are little 'tricks' you can use to help increase your accuracy when using it! Getting very good with your Aqua Bubble and Tidal Wave is the key to being a successful Nami! Keep practicing and soon you'll be ganking so hard everyone will want to be a Jungle Nami ;)
(Read introduction section for pointers)

How Nami fares against other Junglers...

Nami Jungle is VERY bad against the following Champions:
Lee Sin
Jax
Udyr
Vi
Xin Zhao

Nami Jungle is more effective against these Champions:
Dr. Mundo
Hecarim
Nunu & Willump
Trundle
Renekton

Nami is possibly the most versatile support in the game, bringing CC, Utility, and Damage for her team. While at first you might think that Nami has very little damage her early game harass is far stronger than any other support and while it dies off mid/late game the early boost is usually enough to get your ADC off to a good start. I recommend to start with Exhaust and Flash and to pick up Faerie Charm, Sight Ward x3, Health Potion x2, and Mana Potion.

Choosing a starting Ability

Starting off I usually will analyze the enemy Carry and Support. If the other team chooses a Carry such as Ezreal or Vayne I will always start with Ebb and Flow. Since they will likely dodge your Aqua Prison there's little point in starting with it because you'll only end up wasting Mana. However if they choose a Support that can provide a lot of threat such as Blitzcrank, Alistar, or Thresh I will start with Aqua Prison that way if my ADC ever gets into trouble I can easily provide them an escape. The other teams Support weighs more on my choice of starting ability than the other teams ADC. So if I see a Vayne, Thresh combo I will choose Aqua Prison over the Ebb and Flow. There's no point in time where I would ever recommend starting with Tidecaller's Blessing.

Runes, Masteries, etc.

Runes to pickup playing Nami Support:
Mark of Armor x9
Greater Seal of Gold x9
Glyph of Magic Resist x9
Greater Quintessence of Gold x1
Greater Quintessence of Experience x2

Armor and Magic Resist runes will help make you more tanky. You will need Gold and the Experience Quints will help keep yourself from falling behind in levels in the laning phase. Late game you'll still likely become under-leveled but by then you should have a solid start to your match.

As for Masteries I recommend taking the majority of the Utility Tree.

Utility (28):
Meditation 3/3 - You will be starving for Mana, so this helps
Wanderer 1/3 - Filler, however all your abilities provide a speed boost already, so why not?
Scout 1/1 - More Vision? Everyone can always use that! :)
Expanded Mind 3/3 - Again.. More Mana. You need that stuff.
Greed 4/4 - As a passive Support you're going to be broke... seriously. So this will help provide a little more gold and it goes well with your Gold Yellows and Gold Quint.
Wealth 1/1 - This is how you will obtain that Mana Pot to start with! Sustain is huge my friends. :)
Biscuiteer 1/1 - Why this? It comes in handy at that moment when you realize you have no mana or mana pots!
Awareness 4/4 - This will boost your EXP gain to keep you from falling behind in levels while you're off warding the map.
Strength of Spirit 3/3 - This will give you 3 Health Regen per 5 seconds right from the start of the match. Sounds trivial but that's almost the equivalent of a Rejuvenation Bead!
Explorer 1/1 - This ward may only last 60 seconds but it can come in handy early on.
Pickpocket 1/1 - Do you want to become rich? This rewards you for being an aggressive Support! Poke the enemy at every opportunity you can.
Intelligence 3/3 - Cool down reduction for your skills.. This along with Sorcery will allow you to out heal even Soraka early on.
Nimble 1/1 - More move speed? Why not. It compliments your Surging Tides.

Offense (2):
Sorcery 2/4 - This will give you some more cool down reduction for your skills.

Lane Phase Supporting with Nami

How you play during the lane phase will largely depend on your ADC. If you are paired with Ashe, Caitlyn, or Tristana freezing the lane from the start may be your best option and will starve the other team of farm and make it very easy for your Jungle to gank. As long as your ADC is good at farming from under the turret this will enable them to get fed with low risk because the other team will have a very difficult time escaping due to your Aqua Prison and Tidecaller's Blessing and they are going to have to deal with the turret if they attempt to make a play on you. However if you're paired with some other ADC with lower range it's usually best to play aggressive and push the lane up as hard as you can. As long as you ward the grass and always save a little Mana for your Aqua Prison you should be able to escape ganks. During the Lane Phase always land your Ebb and Flow on the other teams ADC and poke both the other teams Support and ADC with Autos (remember you gain gold doing this because of Pickpocket ) whenever possible.

Nami Support is BAD against:

Blitzcrank
Lee Sin
Leona
Lulu
Tristana

Nami Support is GOOD against:

Karma
Nunu & Willump
Taric
Thresh
Volibear

What's that? You think Nami can't ADC?
Well guess again. While I'm not high ELO and you may think it's a troll choice, AD Carry Nami can put a beating on and spar with ANY other ADC in the entire game.
Here is where I am going to show you how.

Getting ready to flood Summoners Rift!

Start off grabbing Ignite and Flash for Summoner Spells.

If you're going to ADC with Nami you will need a good Support to compliment you, this will be the key to wrecking your lane.

I recommend one of these Supports:
#1 Alistar
#2 Nidalee
#3 Taric

All of these Supports have a nice heal which will give you unlimited sustain. Taking Alistar will give you enough CC to completely trash the other teams Bot and even their Jungle if he comes to gank, without even trying. You will be getting double and triple kills and the other team will be left scratching their heads wondering how. As a second choice I would recommend having Nidalee tag along with you. She doesn't have any CC like Alistar but her range, heal, and damage will set you up all game long with loads of kills. As a third option Taric fits well also. He can provide armor, heals, and also a stun that will never miss. Whenever Taric lands his stun on the enemy AD Carry it's a free easy kill for Nami as it will be very difficult for them to escape even with a Support like Blitzcrank or Thresh at their side.

Runes

I recommend a very wide variety of runes for Nami for using her as an AD Carry. The first set I would go if the other team brings a lot of CC to the table, they are the same as my Jungle Nami runes. The second set I would push for when the bot lacks much CC early which would really be the case if the other team takes a Support like Sona or Soraka.

Rune Set One:

Marks:
Greater Mark of Hybrid Penetration x3
Greater Mark of Armor x3
Greater Mark of Attack Speed x3

Seals:
Greater Seal of Armor x5
Greater Seal of Gold x4

Glyphs:
Greater Glyph of Magic Resist x3
Greater Glyph of Ability Power x6

Quints:
Greater Quintessence of Attack Damage x3


Rune Set Two:

Marks
Greater Mark of Attack Speed x3
Greater Mark of Attack Damage x3
Greater Mark of Hybrid Penetration x3

Seals
Greater Seal of Attack Speed x9

Glyphs
Greater Glyph of Attack Speed x9

Quints
Greater Quintessence of Hybrid Penetration x1
Greater Quintessence of Attack Damage x1
Greater Quintessence of Attack Speed x1

Masteries

As ADC you need damage, thus for ADC Nami the Offense Tree is where you want to put the majority of your points.

Offense (26)

Summoner's Wrath 1/1 - This will give you a tiny bit more damage when your Ignite is down.
Fury 4/4 - More Attack Speed.
Butcher 2/2 - This will make your farming a little less painful, believe me! x)
Deadliness 4/4 - More damage.
Destruction 1/1 - More damage to turrets? Why not.
Havoc 3/3 - Even more damage.
Weapon Expertise 1/1 - Big help against Supports that start off really tanky early.
Lethality 2/2 - More Crit Damage.
Brute Force 2/2 - Damage, Damage Everywhere!
Spellsword 1/1 - Why take this on an ADC? Because with Hextech Gunblade, Guinsoo's Rageblade, and Elixir of Brilliance you are going to slap some puppies really hard.
Frenzy 1/1 - 10% more Attack Speed? Oh yuss pls(;
Sunder 3/3 - You won't even be able to tell they bought that Thornmail. Be sure to ask them why they wasted all that gold.
Executioner 1/1 - This not only helps on Champions, but your farming too. You will get good use of this the entire match.

Utility (4)

Summoner's Insight 1/1 - Decrease the cool time on your Flash.
Wanderer 3/3 - More move speed is always nice.. Especially when you have Surging Tides as your passive.

Crash the party, with a flood.

"Y U TROLL?"
"NAMI ISN'T ADC!"
"NU PLS NOT NAMI ADC."
"AD NAMI????!!!!"

This is what you are going to hear when people find out you are going AD Carry Nami. However you are the party crasher AD Carry Nami and not only are you going to blow your teammates minds, but you are going to wreck all enemies who stand in your way as well.

After spawning pick up a Long Sword, Health Potion, and Mana Potion. You can even start with a Doran's Blade if you want. Do you want to know why? Because unlike any other ADC, you can heal yourself. If you have Alistar, Nidalee, or Taric.. They can heal you too! Thus you have absolutely no risk in starting with the pure damage item. Wuts dat? Nami sucks? Think again.

Early on, you will win 100% of all trades. It sounds stupid, but the fact is.. even if you run out of Mana you are a threat and can still hurt the other team. Upon recalling for the first time I recommend grabbing Tear of the Goddess, Bilgewater Cutlass, and another Long Sword if you can afford it. Next whenever you are able to buy time and can afford them pick up a B. F. Sword, Berserker's Greaves, and upgrade your Bilgewater Cutlass into a Hextech Gunblade. Now you are likely thinking, why would you go for a Hextech on ADC Nami? For a few reasons. First off since we are using the Spellsword passive the AP is now going into your auto attacks. Second, it will increase your self heal as well as the damage for your Tidecaller's Blessing. It also gives you some Spell Vamp off your Tidecaller's Blessing which will increase how fast your health regenerates when combined with your Life Steal. This also goes for Guinsoo's Rageblade which you will get later.

At this point you should have Berserker's Greaves, Tear of the Goddess, B. F. Sword, Hextech Gunblade, and possibly a Long Sword. The next item you will want to get is Bloodthirster. After you grab that, upgrade your Tear of the Goddess into a Manamune. The next item to get is up to you. You can grab a Phantom Dancer or Runaan's Hurricane for some Attack Speed, or you can get Guinsoo's Rageblade for more damage. I recommend Phantom Dancer because of the increased movement speed and crit chance however if you find yourself in need to clear waves of minions faster Runaan's Hurricane may be a better option. If things are going smooth and you're slapping your enemies in the face like you should be however, I would grab the Guinsoo's Rageblade as it provides everything you need, Attack Speed, Damage, Ability Power, and even more Life Steal and Spell Vamp if you find yourself in a pinch. Finally upgrade your boots with Enchantment: Furor so that every time you hit an enemy with your auto attack you gain a speed boost.

Remember, there is no try! Only do! Everything is possible and the many forms of Nami is no different. Learn your Nami well and it will treat you well. :)

I'm currently experimenting with Solo Top Nami and Nami Middle. More to come in the future, so if you love Nami as much as me then keep checking back for more.

If you have any questions or comments post and I'll be sure to read.
In the mean time up vote so all can see just how amazing Nami really is! :)