This is my first guide so any feedback would be appreciated. Note: This is a guide not a build so please read through and test it out before you vote. This is a guide for Tristana. She has really high burst damage giving her a high chance to kill in lane. Also Tristana passive gives her the highest range of any AD carry at level 18 surpassing even Caitlyn.

EDIT: 4/6/12added

• in-depth skill section
• burst combo section
• added Frozen Mallet to item section
• And this guide has over 500 views! :D Thanks everyone!
• Now nearly 7,000 views! :D Thankyou!!
• Making some changes after a few changes with the meta

Pros:
Cons:

• -Squishy
• -Early game auto attack damage is lower then some other AD carries
• -Very vulnerable to cc
• - Rocket Jump acts as a dash rather then a jump (see summoner spells)

• Okay so lately, I've really liked taking 19/0/11 because if you start Doran's Blade then you will have an extra 80 hp and you get 9% life steal at early levels this is really nice to have to make and heal from trades.

• Now lets talk about the runes
• I take AD reds Greater Mark of Attack Damage because they give you an early because they help you farm because they give more damage per shot. This also helps when you poke your enemy.
• Combined with Armor yellows Greater Seal of Armor you should be able to trade shots with your opponent easily.
• Also MR blues Greater Glyph of Magic Resist to help resist some of the pokes from supports who deal AP damage such as Sona, Lulu, Taric, etc..
• Lastly Life steal quints Greater Quintessence of Life Steal to let you start Doran's Blade you get incredible early sustain, it also lets you skip a vamp scepter in lane. ^_^

My personal choice is:
Defensive! and
This is a really safe choice because in any fight, whether it be in lane, or team fights, if the enemy team dives on you, 2 defensive spells should be enough to save you!
Offensive! And
Why heal + ignite? Well Tristana has a personal ignite Explosive Shot so you can jump in, double ignite, kill, jump out.
Good summoners for Tristana

• This is good when your being chased or in A 1v1 situation with the opposing AD carry
• This is a really good summoner if the opposing team has someone with ridiculous cc such as Fiddlesticks or Malzahar but buying a Quicksilver Sash has the same effect although qss isn't usually in my core build, so if they do have a lot of cc, then this is a nice spell to grab.
• If the team has good champs with gap closers which cancel out your Rocket Jump then this is a good escape

Not so good summoners

• Not really useful as long as you play smart
• Your not jungling...
• Well this could be useful but since we have Rapid Fire (90% steroid) and we aren't AP this isn't a good skill for this build
• Really..? Okay well just conserve mana which makes this useless.
• This is useful but there are far better choices
• Leave this for your supports

Increases Tristana's attack speed by 30 / 45 / 60 / 75 / 90% for 7 seconds.

• Okay this is Tristana steroid which at level 5 gives a 90% attack speed increase!Okay so late game this can get your attack speed to well over 2 attacks a second which when your getting those devastating crits for well over 600 to squishes you can easily melt there whole team

Tristana fires at the ground to propel herself to target location, dealing 70 / 115 / 160 / 205 / 250 (+80% of ability power) magic damage and slowing surrounding units by 60% for 2.5 seconds when she lands. On a champion kill or assist, Rocket Jump's cooldown resets.

• This is the bread and butter or your burst combo. 250 damage at level 9 is a huge burst up to about a quarter of the opposing carries hp finish the combo throw a few AA (auto attacks) and you'll win any trade and more then likely get the kill.
• Rocket jumps a dash?!?!? Well yeah. It has a jumping animation but while midair you can get caught with cc such as Alistar and his cc, Malzahar's ult, etc... So just remember whatever would hit you in Graves Quickdraw will hit you during your Rocket Jump

Passive: Enemies explode when slain by Tristana's attacks, dealing 50 / 75 / 100 / 125 / 150 (+25% of ability power) magic damage to nearby enemies.

Active: Explosive Shot rends the target enemy, reducing healing and health regeneration by 50% and dealing 110 / 140 / 170 / 200 / 230 (+100% of ability power) magic damage over 5 seconds.

• Now this is your personal Ignite also its your farm machine! Something really nice is if the opposing ad carry is by the minion you kill at level 4 you deal 75 free damage that's a decent poke follow with an AA you'll deal about 150 DAMAGE! at level 4 that's more then 10% of most ad carries hp, that's really nice imo.

Tristana fires a massive cannonball at an enemy unit. This deals 300 / 400 / 500 (+150% of ability power) magic damage and knocks surrounding units back 600 / 800 / 1000 distance.

• Buster Shot with 300 damage at level 1 is crazy! This is the biggest amount of damage in your burst combo. With this you can Rocket Jump just past your opponent Buster Shot towards your support and your practically guaranteed a kill!

So first off why take two levels of E before Q? Well early game majority of your damage is from your burst combo so the more damage you can do in the burst the more chance youll secure the kill.
Next why max Rocket Jump? It does the most damage at one time, its your escape and gap closer, this is what you'll engage with.

THE BURST IS TOO STRONG!

• You jump in with Rocket Jump -> ignite with Explosive Shot -> Buster Shot which you follow with an auto attack -> Ignite -> Heal -> Rocket Jump away to safety

Lets do some math here

• okay your laning Ashe this is just gonna be raw damage no armor included. It's level 6 you both have 2 Doran's Blade Ashe has 990 hp. At level 6 you have 3 points in Rocket Jump 2 points in Explosive Shot and one point in Buster Shot
• Your AA deal 90 damage per shot
• Okay so Rocket Jump does 160 damage Explosive Shot does 140 over 5 seconds and Buster Shot does 300 damage and Ignite does 170 damage
• 160 + 140 + 170 + 300 = 770 okay thats over 80% of ashes hp and heals are worthless from the double ignite remember: this is all in a matter of seconds.
• 990 - 770 = 220 220 / 90 = 2.4
• That means in one burst combo you can kill ashe with just 3 more auto attacks. Imagine if you had an really early B. F. Sword!

NOTE: THIS ISN'T THE BUILD FOLLOW THE ITEM GUIDE BELOW
Should you start dorans blade or Long Sword and potions?
Blade
Okay so Doran's Blade gives you 10 AD 80 hp and 5 hp per hit I'd take this most of the time, especially if you have a support with a heal to sustain you Soraka, Sona, Taric
Long Sword
Take Long Sword and 2x Health Potion if you have a support who can't sustain such as Blitzcrank, Janna, or Lulu and you're in a lane you'll get bullied in, such as laning against Caitlyn, Draven, etc.

What items do you build next?
Okay if you bought Long Sword first then buy a Vampiric Scepter and Berserker's Greaves. If you started with a Doran's Blade buy Boots and a B. F. Sword this is standard opening

Core items

What do you build after the sword? (early game)

• If you need sustain build a Bloodthirster
• If you're winning your lane by a lot and you can get it before 19 minutes,buy Infinity Edge + Vampiric Scepter

Damage items (Mid game)

• Build three of the following:
• Buy a Infinity Edge if you built a BT before and build a Bloodthirster if you build IE before
• If the enemy team is stacking armor build a Last Whisper
• if the 3 or more of the enemy team has 2600 or more hp build a Blade of the Ruined King
• You need attack speed so build a Statikk Shiv this will help you with your weak mid game. Later trade it for a Phantom Dancer

Defensive items

• Build one of these:
• If you're getting focused in team fights buy a Guardian Angel
• Facing someone with ridiculous cc? Quicksilver Sash
• If your dying to tons of magic damage Banshee's Veil
• If there are 3 or more ad champions on the enemy team Thornmail
• If your dying to easily and/or the enemy is bursting you, buy a Warmog's Armor this will make you beefy and ensure the kill

Okay well that's my guide for Tristana remember the burst combo above and you should be fine. Tristana is very easy to learn for beginning players. I hope you enjoyed and Don't forget to comment and vote :D