I realize that it is a long guide after I wrote it, but please read every bit of it, knowledge is power, knowing every last bit of insight on Tristana will win you your lane.

Revised (2-18-2011):After I hit 1500+ elo, realize that I should probably update my guide since many patches been out.

The Basics
I am writing this guide for two reasons, first is dedication to my friend MangoWorks as she loves Tristana with all her heart; the other is that the two other good guides on this website (Mergling gunner and doran's blade massacre) are out of date for Tristana especially with the evolution of the meta and higher level games. This guide is intended to explain to newer players how to play Tristana and a solid build for more advance players.

Runes

Quintenssence - 2 speed quints and a armor pen quint, 2 speed quint will bring u to 309 speed, which is on par with most champions.

ArmorPen Marks
It makes your attack penetrate 18 of the target's armor plus the 6 that you get from your offense mastery, you're doing 26 more damage to the player.

Hp Regen seal & Mp Regen glyphs
These are optional, as in you can pick your favorites. These two categories of runes provide minimal usage for Tristana Early games. Hp Regen keeps you in lane that much longer. MP regen is because Tristana does burn quite a bit of MP early game to harass.

Other options for seal and glyphs
Crit Damage and Crit Damage - It adds a nice chunk of damage late game, but the point of runes is to give you a solid advantage in the beginning of the game which leads to a great end game. If you have a good early game, those extra critical damage at end games are minimal as you would be fed.

Health regen per level seals and health regen glyph
These two are good sets too, it makes you regen faster than your enemy which means you can trade shots more often and stay in lane longer.

Mastery
21 in offense to maximize your damage, 9 in utility to grab more experience. Some mastery are self-explanatory, you may question why I take 15% magic penetration over 4% attack speed, the reason being that from level 1-11 your damage will primary come from your skills W,E,R, that 15% magic pen will aid in those damage burses.

Skill Build
Why E first?
Simple, E on passive will explode minions for more damage to the surrounding making last hits easier and sometimes you will kill nearby minions with that explosion.
E on active will drain enemy life. At level one, it drains about 20 damage for 4 seconds after enemy magic resistance. At max level, it will drain 20 damage for 9 seconds.
E is your primary harassment skill as it also reduces healing rate. Main reason is that you can harass them from distance in addition to your regular attack range. Something really nice to do is a triple harassment threat of Regular attack >> E >> regular attack. The time it takes for Tristana to fire E is the EXACT cooldown time between your first regular and second regular attack, making 2 attacks with E in the middle a perfect combo. (after that, you normally will have 49365793267 minions banging on you because you just banged the opposing team's champion for a good chunk of their health) That takes about 200 of their life away as your regular attacks will do about 50-60 damage each and E will do 100ish. Do it a few times, and they will have to run back to base to heal leaving you alone to stab at their tower.

BEWARE!: Tristana's E will ALWAYS push your lane, so make sure to only last hit to avoid jungle ganks. This also makes going to mid lane crucial, w and flash will bring you back to turret, along with R, you're a kiting god.

Why W next?
W is one of your early game damage burses. It will do another 100-200 damage to your enemy depending on level.
W is one of your best chasing and escaping mechanisms. See a gank coming your way? W back to your turret. Missing that one last hit on a champion kill? W in to kill them.
W resets on kill which means super easy tower diving, because of the fact that W resets on a kill or assist, if you dive into the tower for that last hit, W will be your diving out after you killed them because it would reset instantly.
W is a commitment every time you use it to attack an enemy. Because using it means you're positioning yourself right next to them shooting them in their face. It is a commitment because you are putting yourself at close range vulnerable position. ONLY USE W ON YOUR ENEMY IF YOU CAN KILL HIM FOR SURE OR IF HE'S USED UP ALL HIS SPELLS ON MINIONS BECAUSE THEN WHEN YOU JUMP ON HIM YOU CAN ATTACK HIM AND USE YOUR E ON HIM WHERE AS HE HAS ALREADY USED UP HIS SPELLS ON THE MINIONS. Everytime you use W on your enemy it should scare them into running fearfully hence putting a psychological effect on them and boosting your own ego. (Come on! are you telling me that you don't like seeing enemies running away? I love it everytime I W in and they run away, I literally say behind my monitor screen, "*****! that's right, you better run, big daddy is coming to get you."

How to abuse R
Tristana has one of the BEST ultimates in the game because it is an multipurpose ultimate.
See a Nunu channeling his ult? Blast their ***, See a Fiddlestick running in with his channeled ultimate? Blast his ***. See a teammate getting chased? Blast the chaser's ***! See someone with 200 health? Blast their ***! See Katarina spinning like a crazy ***** thinking that she can kill you just like that? Blast her ***! See a cocky *** you want to kill? W behind them and Blast their *** back to your tower or teammates and watch them run slowly out of it while you shoot them to hell.

Yes, Blast the **** out of them. Literally, Tristana's ultimate can be used to stop other people's ultimate. Most of the time are people that channel their ultimates. It can also be used to help your party. Often times in late game, you will see people using their AoE ultimates like Kennen with his Maestrom and Fiddlestick with his crowstorm, that requires them to be in range to you, if you blast them back, that's enough to stop them because they would have to walk all the way back to you again to do damage and by then, their ultimate would have already wore off making it useless.

Yes, Blast the **** out of them. Literally, Tristana's ultimate should be your last hit on champion heros level 1-10. If you want to use Tristana effectively, you better learn how to calculate your damage. What I mean is, if you harass your opponent enough times, they would be at about 400-500 health. The art of Tristana is the number of ways you can kill them with. W in blast the **** out of them. W = 100-200 damage, R is 300 damage at level 1 after magic resist, it should do about 250 damage, that itself is already 350-450 damage, it would only take you a few shots to kill them. But the order should really be W in and use your regular attack until they have low enough health blast them to hell with your Ultimate.

Why Q last?
Simple, what good does it do when you spam your Q to attack 90% faster when each of your attack only does about 50 damage? Where as late game, each of your attacks crit for 500 damage, you can attack 90% faster at a much more effective attack ratio. Bottom line is, Attack Speed is **** without attack damage and vice versa. If I had to choose, I would say attack damage comes before Attack speed simply because if enemy team is good, you'd be running more than shooting, so higher damage > higher attack speed.

Items Build
You ALWAYS start with doran's shield. 8 regen per 5 is godly and here's why. in one minute you regen 96 health on top of your regular regen. And it is better than any item you can start with. Vam scepter? 12% lifesteal, what good is that item if your enemy is so good that they press you against your own tower unable to hit monsters? The weakness of lifesteal is you need to hit the monster for it to work. So everytime I see someone with doran's blade or vam scepter, I abuse them by keeping them away from my creeps. Remember if you trade hits, doran's shield will give you a 120 hp advantage, you will ALWAYS push them back. Doran's blade? 100 health 9 ATK! AND 3% LIFESTEAL! Honesly, 9 attack is literaly nothing. And on top of that, for that 3% lifesteal to match the 8 second regen per 5 seconds, you need to do 240 damage in 5 seconds to creeps. BUT! what if there are no creeps around? And suppose you do, you will have to continously attacking which means you will miss quite a bit of last hits. Those with experience will know that lasting hitting minions takes patience to wait for the minion to get to low health by minion attacks and you just attacking in for the last hit.

Revise: In higher level games, you will get ganked, and you're going to be forced back to shop and heal more, in that case, doran's blade is more helpful. Stacking them will increase your survivability. Additional damage will help you last hit easier and faster. Doran's blade stacking very good still even after the cost nerf to doran items. You do not have to stack 3, or stack at all if you feel that your team is there to cover and counter gank for you.

Other item to start with include cloth armor + 5 red pots, or shoes + 3 red pots. The point of those starting items is for the pots, so that when you trade hits with your opponent, so that you will have health pots to fall back on. But most of the time you would be forced back with about 1k gold or less, and usually the best item to get from there is doran's blade.

Core item for ANY dps is always Infinity edge. Tristana's late game damage will come primarily from basic attack critical damage. Always get infinity edge first, unless you're forced to go back to base because of low hp or lossing a battle. In that case you can buy your boots too. I like zeal after that, because of the movement speed with the additional critical chance. Then the last whisper, this is a crucial item, +40 atk dmg and 40% armor pen, your damage against any tanks after that will be golden no matter how much armor they have.

Variations after that, is you can either finish the phantom dancer, or grab a banshee for survival, trust me, in higher level game play, there will be 2 tanks and 1 anti carry after your ***. Getting that initial stun off you will help ALOT.

I can guarantee you that at higher levels, every player adjusts their item builds to the champions that they are playing against. Madred's bloodrazor is a wonderful items if your opposing team are full of bulky guys or tanks. Bloodthirster if you find yourself trying to out damage the other team's dps, thirster builds up from minion kills giving you a total of 100 damage and 25% lifesteal after killing 40 minions or creeps. (I personally do not like Bloodthirster, you lose the bonus if you die) Frozen mallet is good only for survivability against the people that chase against you, gives you ashe-like kiting power. And boots depending on the other team, Mercury's Tread for if you are playing against lots of stun and slows other wise boot of mobility, makes you run like a little fairy and you will love the speed boost with that and phantom dancer. PLEASE DO NOT BUY BERSERKER'S GREAVE, REASON IS BECAUSE THERE IS ONLY ONE ITEM IN THIS GAME THAT GIVES YOU MOVEMENT EFFECTS AND TEN OTHER ITMES IN GAME THAT GIVES YOU ATTACK SPEED. The 25% attacking speed from berserker's greave can be made up with other items.

Gameplay
Tristana's job is to DPS down those caster and squishies while keeping herself alive. Tristana is a squishy does not mean she shouldn't be in the front line. She should always be at the front line with the tank before the team fights starts. Because of her passive ability, every level she gets, her range gets more ridiculous, so use it to your advantage and pick the enemy team health slowly. If the team fights starts with everyone jumping on you, please do yourself a favor and W to the back of your team or flash out. Tristana is best if she stands on the side and pick away the enemy team squishies and DPS.

Things that you should not do with Tristana.
-Run back to base during a team fight with 200 hp. (Seriously? you got hurt a bunch and you want to head back? BAD mistake, abuse your range and just shoot from afar even if you're low health, your damage makes a big difference for the team fight. So stay far back if you are low on health and attack away.)
-W in the middle of everything. (I so often see higher levels W in the middle of a team fight to maximize the AoE damage of W, NOT WORTH IT, YOU WILL DIE IN TWO SECONDS)
-Risk yourself getting killed for a kill or chasing enemy team alone. (A living Tristana is infinitly more useful than a dead Tristana)

Things you need to do with Tristana.
-Last hit, Last hit, Last hit. (you need 4080 gold for infinity edge which is about 150 minion kills. Taking middle helps, Killing an enemy helps.)
-Abuse your range and harass. (you can almost always push the enemy back to their tower because of your E passive will let you kill their minions faster, your range will harass them)
-Jungle! (Before you head back to base, take a look at your mana, if you got 200 health but 500 mana, it is a waste to just go back to base like that. Do yourself a favor and grab the 50-80 gold on the wolve camp and wraith camp on your side of the forest. W in and last hit and everything will explode.)
-STAY IN YOUR LANE! (You are far too weak and slow to go between lanes to gank, and the time wasted between commuting is not worth it. It will put your gold farming way behind and you will end up lossing the game because when the time comes for you to burst your dps, you can't becuase you didn't farm enough gold to buy the items necessary.) Save your teleport to help other lanes.
-Abuse your escape mechanism. (W can jump over walls, basically you should almost never die when a gank comes for you. A stun of two seconds shouldn't be a problem becuase W and Flash will make yourself at your turret again.)

Summoner skills
Teleport and Flash FTW, Teleport lets you shop without losing laning time. Tristana is really slow, going from lane to lane isn't efficient, teleport will help with that.

Flash is just sick, most amazing skill ever. Try to use it only to save yourself, or for sure 100% gives you a kill.

To me, summoner skills are just personal playing styles by all means replace it with what you like. For me, flash and Teleport are both survival skills for Tristana, because she is a squishy after all. On winning games, I usually only die once or twice. On lossing games no more than 6 times. That's my personal record. =P

Knowing Your Enemy
This is important, as who you lane against will either break or make you.

-Champions you should ALWAYS EAT for BREAKFAST, LUNCH, AND DINNER:
Ashe: Seriously, she has no harassement skills, hide behind your creeps and harass her with your longer range and E.

Teemo: Blind and poison? Just micro it; run back if blind, atk E atk combo and harass, you have longer range.

Rangecarries/casters: Namely veigar and annie You out range them, E is better than most harassment skills out there.

-Champions you should be caution of:
Anivia: Her passive will give you trouble, because it is not worth it for you to turret dive, as they will reborn full health under the turret fire. Solution - chip her away, and finish her off once with your ult without diving the tower, most anivia's will be fearless thinking they have their egg to back them up. Kill them once, they will become *****birds.

MordeKaiser: This chunk of metal is so cheap, he will kill you anyday before you kill them. Luckily, they are so useless late game, you just eat them alive then. Solution - Mordekaiser has that rigged shield, so just stay away from your creeps and focus fire on taking down enemy creeps for last hits. As long as you don't let him kill your creeps first, you won't be pinned against your tower. You can jump him when all your creeps die, because he will have nothing to give him shield, please take note of his creep before you do this, creeps are op.


Pantheon: Rarely you will see this guy in mid laning against you, but it will happen in higher level games, or one day by random chance. He jumps you and you will be stunned, you are helpless but to watch him take you down with Heart seeker strike. And when you try to harass him, his stupid fat shield will block your attack. Solution - Stay away from him, he runs towards you, you run back. He is not efficient at killing minions, unless he uses the spear attack which will waste his MP, harass after he uses his spells. As for his blocking passive, feed him a big fire cannon ball. (E skill)

Morgana: Pro morgana's are godly, she's tier one. Spell shield will block your E, her passive 15% spell vamp will make your attacks look like jokes as she recovers so fast. Solution - Morgana depend on her demented soil on your creeps to recover, hit her before she casts that, make sure you run around like a crazy person with unpredictable movements so she can't trap you with her Q. Bottomline is, if you can pin her back before she gets higher level, you will be good. W in after she use her demented soil on your creeps.

Missfortune: She runs so fast, she's going to rape you with double-up everytime, landing a second shot on you. Solution - Poke her every chance you get, so her passive cannot activate, just tell her you're jealous of her speed. Stand to the side of the creeps, do not let her line you up with a creep and double up will be nulled. Sure she can hit you with the first shot of double up, but remember, you have longer range, Atk E atk, will make you do more damage to her.

Sivir: Her boomerangs are really easy to dodge. But, her true power is the pushing ability. After a certain level, she will kill a whole wave in 2 seconds. Hopefully, you will be farmed enough to take out minions fast enough with your E passive.

Urgot: Avoid his Corrosive charge, if you get hit, jump back before he does too much damage to you with homing.

LAST BUT NOT LEAST, PUSH, YOU DON'T WIN THIS ******* GAME BY KILLING YOUR ENEMY 99999999 TIMES. YOU WIN BY KILLING THEIR ******* NEXUS SO OWN YOUR LANE, HELP PUSH OTHER LANES, CHIP AWAY AT ENEMY TOWER EVERY CHANCE YOU GET.