This is a build made by myself, after trying out most of the builds around mobafire I still couldn't perform as good as I can with this build.

Tristana is a hard carry, specially on late game, take the bottom lane with a support champion controling the bushes for you, letting you farm the most you can, your range is truely amazing and you can deal with probably anyone due to it.

She is a great pick against healing champions, such as Doctor Mundo or Sona for example, countering them perfectly.

Pros

- Extremly insane late game DPS ;
- Longest range in the whole game, which is perfect for taking a carry spot ;
- Aint an Attack Speed item dependant carry due to her insane Rapid Shot ability ;
- Has two abilities who can both be used as offensively and defensively, her W and R ;
- On team fights she can simply just auto-hit from a far away distance and melt her enemies while being pretty much safe.

Cons

- She's a complete Glass Cannon, your positions determines everything ;
- Her carrying ability is mostly only noticeable when you reach late game ;
- She relies a LOT on items, making her a LOT item dependant ;
- Due to the recent nerfs on every ranged carrie, it makes her pretty slow while moving ;
- You'll always need to have a good supporter on your back while being on competetive play.

About the summoner spells it's also pretty simple, any ranged carry should always take most defensive spells you can have, which usually always are Flash combined with Ghost.

Oh well, but as we know Tristana has her own escaping skill which can be compared to a flash, called rocket jump, by that logic you can avoid taking flash.

I would usually take cleanse instead for that reason, making it easier to prevent yourself from being stunned or being hitten by any sort of cc transforming you into easy meat to whoever tries to kill you.

Obviously there are other few possible options, which I would only consider in exchange for Cleanse, those would be Flash or Exhaust only.

There is no other reason to take any other spells, I have seen on most guides here recommending to take Ignite, but what for?
That doesn't make any sense on a physical carry, specially Tristana which has her Explosive Shot ability which has the same effect Ignite has.

All the other Summoner Spells are a complete NO, do not EVER take them.

These are the best reds to take if your objective is to deal dmg, specially on early game, you'll notice it a LOT.



The choice to take this runes is obvious, Tristana has a low based mana pool compared to the costs of her abilities, taking these two pair of runes let you spam abilities as much as you desire to.



The reason behind this Quints is the same as the one who will make you take armor pen for reds, insane dmg output.

Tristana can safely farm and harass her enemies, but also, she can jump out of nowhere and assure her kill. Keep using your long range shots till your enemy gets around medium/low hp, then just jump into them with your rapid shot skill enabled get him your Explosive Shot and shoot him down, if necessary use your ultimate to finnish it.

There's also the most basic tactic for tristana, you turn on your ghost, jump to your enemy's back and use your ultimate to push him into your turret or next to your mates, after that, well, just finnish them off easily.

Tristana is also great to tower dive those lucky ones who remain on low health after a fight and go to their tower blue pilling, well, just jump into their face, ulti asap if needed and jump back instantly after, you should get hit in maximum only twice by the turret, it's easy as a pie.

Also, an essential part of tristana, if possible always take always the red buff when available, you can also go steal your enemies buff pretty fast, leave mid for a second when you know it's safe and get into the bush to do theirs safely.

This was all written on some fast rush, but trust me, it's reliable and it works like a charm.

About the initial item after the Doran's items nerf, it's even more situational, if you gotta go for solo top or solo mid, you should always take a Doran's Shield.

If not, and if it is possible for you to go bottom and play where you are supposed to, with a support on your "back", you should take a Doran's Blade, that's for sure.

You should always rush for a BF Sword, Tristana is one of the easiest champion to land last hits, due to her Explosive Shot passive so it shouldn't be that hard.

You should at least have a BF sword and a regular pair of boots on your first or second trip back to base, after that just build up your Mercs.

The boots choice is pretty simple, the ammount of CC and AoE nowadays wins matches with the current meta game and Mercury Threads are just the best overall boots, specially for Tristana that is a glass cannon.

The next item is followed up by Emblem of Valour, due to the simple fact you'll need and want some life steal.

After that, what you'll need is some defensive item because while being the carry you will usually always be the one to be focused first, that's obvious.
You should get a Banshees Veil ASAP, it is probably one of the best items in game, not mostly due to the defensive stats it gives, but instead, due to the shield block passive, which will make it harder for your opponents to initiate on you.

The following items are also obvious picks, Last Whisper for his short cost gives you higher dmg and a nice Armor Penetration percentage to also take down the enemies tank(s) possible armor items existance. This item scales nicely with your runes and your possible following items.

Now you will need to finish your third item pick, Emblem of Valour will now be envolved into Stark's Fervor, which will finally give you some extra Attack Speed and some more Life Steal.
It will also offer your team a nice aura, specially if you're not the only DPS dealer on it, and that's not everything, it also reduces nearbie enemies armor which is AMAZING for you, and still, it offers more Health Regenerating, Attack Speed and Life steal to your allies.

The very last item is the one I find the most situational at all, my choice would be between The Black Cleaver or Frozen Mallet.
If you're having a hard time while catching them or if you need more survivability, go for Frozen Mallet.
Otherwise, if you are having problems while dealing dmg or need more attackspeed, you should go for The Black Cleaver which will help you by a LOT specially due to it's Passive which will stack perfectly with your previous items.