Lulu is a very strong support through all phases in the game. She has very strong poke early on and very good kiting and champion saving abilities in the mid to late game.
I will be running through Lulu's common botlane encounters and potentially the best ways to them, i will also go into team compositions she works well in and reasons why you may pick Lulu.

There are two sets of runes i like to run on Lulu and it depends on how aggressive your lane opponents are.

Vs Burst lanes: (Blitz, Leona, Taric, Thresh, Ezreal, Graves, Varus, Quinn to name a few)

I take double armour runes on Lulu against aggressive lanes because without it you become very squishy and can get burst down easily, taking extra armour also make your shield and ultimate more efficient when you use them on yourself. Mana Regeneration is also a must with Lulu as you will want to be spamming your abilities as much as you can both offensively and defensively.


poke/defensive Lanes[: (Janna, Soraka, Nami, Sona, Ashe, Miss fortune, KogMaw)

When against squishy lanes you want to be poking hard and aggressive as possible the mana quints help you spam abilities and the Magic pen allows for extra damage from the base stats on your abilities.

Summoners you will always want:

These are the masteries I like to use on Lulu 0/9/21 http://i.imgur.com/PBuLYsQ.jpg

Glitterlance (Active): Lulu and Pix each fire a piercing bolt dealing magic damage, slowing enemies hit by 80% for a short duration. This slow decays over time. An enemy can only be damaged by one bolt.
Cooldown: 7 seconds
Range: 925
Cost: 40 / 50 / 60 / 70 / 80 mana
Magic Damage: 80 / 125 / 170 / 215 / 260 (+0.5 per ability power)

Slow Duration: 1 / 1.25 / 1.5 / 1.75 / 2 seconds

Whimsy(Active) – On ally cast: Target ally gains 35% movement speed and bonus ability power for 5 seconds.
(Active) – On enemy cast: Polymorphs an enemy champion for a short duration, disabling their ability to attack or cast spells and reducing their base movement speed by 60.
Range: 650
Cost: 65 / 70 / 75 / 80 / 85 mana
Cooldown: 18 / 16.5 / 15 / 13.5 / 12 seconds

Bonus Ability Power: 20 / 30 / 40 / 50 / 60

Polymorph Duration: 1.5 / 1.75 / 2 / 2.25 / 2.5 seconds

Help, Pix! (Active) – On ally cast: Commands Pix to jump to an ally and then follow and aid their attacks instead of Lulu's for 6 seconds. Upon arrival, Pix shields them for 6 seconds.
(Active) – On enemy cast: Pix deals magic damage to target enemy unit. Pix then follows and grants vision of them for 6 seconds.
Cooldown: 10 seconds
Range: 650
Cost: 60 / 70 / 80 / 90 / 100 mana
Shield Strength: 60 / 105 / 150 / 195 / 240 (+0.6 per ability power)

Magic Damage: 80 / 130 / 180 / 230 / 280 (+0.6 per ability power)

Wild Growth Lulu enlarges an ally, knocking nearby enemies into the air and granting the target ally a large amount of bonus health. For the next 7 seconds, that ally gains an aura that slows all nearby enemies.
Cost: 150 mana
Range: 900
Cooldown: 110 / 95 / 80 seconds
Slow Percentage: 30 / 45 / 60 %

Bonus Health: 300 / 450 / 600 (+0.5 per ability power)

You can max the Q first on Lulu, the Q does more damage than the E but if you Max the E it still does good damage; it allows you to have a stronger shield, so i find maxing E if the much more efficient option.

Starting: >> Sight Ward X2 >> X2 >>

Now this is where your build becomes stituational, if you are against lanes with burst like i explained before you will want to buy your items in this order >> Philosopher's Stone >> >>

If you are against lanes with poke the build order i find most effective is
Philosopher's Stone >> >> >> >>

Mid Game:
If your team needs to be more tanky you want
If your team is ahead and want to initiate fights i recommend
If the enemy has hard CC Such as Stuns, Snare or Slows this is a must
A very situational item is & These items can be picked up if the team you are against has fast champions for example Quinn, Singed, Hecarim, Nidalee.
If you just looking to give your team higher endurance then you want
If it get very late in the game and you are looking for some tanky items then you have a few options
If you want to try and do some damage (not recommended) then these are your options

Pros:

High poke damage early
Very strong CC
Can protect the carries very well
Her E gives vision of invisible targets

Cons:

Can be burst down easily early on
Fairly high mana costs
Has trouble against people who build sustain items

Lulu has so much to offer a team from defending carries to to chasing enemies, here are some champs lulu will synergies well with and counter.

& : Lulu works well with all ad carries but these two in particular are hyper carries and the longer you can keep a hyper carry alive the more enemies will die. Lulu's Wild Growth will give your carry a burst of health meaning they can shell out damage for much longer.

& : These two champs have a hard engage that knocks everyone up that they hit, using Lulu's Wild Growth on these champs will cause everyone around them to get knocked up for a second time if you can time it correctly. This creates a lot of time where the enemy is up in the air and allows your team to put down some serious damage before the enemy team can even move.

& : These two champs engage by running into the enemy and throwing a champion back into the team using Whimsy you can give these champions a speed boost to allow them to catch the champions they want and one they catch some one all you need to do is hit them with Glitterlance and they are not going anywhere.

Champions who are heavily ability based: Assassins fall into this category mainly, Lulu is very good against these champions because using Whimsy on an assassin will not allow them to pull of there combo and they will be vulnerable to your team attacking them for a short while. Lulu's Wild Growth also can stop carries from getting bursted down instantly giving you team enough time to kill the assassin.
Champions who have channeling abilities also suffer hard against Lulu, such as & & When Lulu uses Whimsy on these champions while they channel there abilities it will cancel it instantly meaning they will lose out on a lot of damage and will become a little kitty for a short amount of time.

Lulu in my opinion is the best all round support, she has great defensive abilities and strong offensive abilities. She can go up against all match ups without being punished hard, you need to make sure you have good vision of the bushes inlane and ones in the river.