I am summoner CheesyBoy8 and Tristana is the second ADC which I mained. I feel she is the best hypercarry especially in 8.15 even with the nerfed crit items from earlier in the season. She has a great carry potential.

Flash and barrier is what every ADC takes at the moment especially hypercarries. Barrier gives more survivability in lane and in 1v1s so is better than heal. Plus, you take flash on every champion.

If you find yourself in a hard matchup take Doran's Shield yet if you want to have an aggressive laning phase take Doran's Blade. My ideal build on Tristana is:
BF Sword
Rapid Firecannon
Statik Shivv
Infinity Edge
Bloodthirster
Mercurial Scimitar
I sugeest using Ninja Tabi or Mercury's Treads as boots as it gives more survivability in the late game where you need to stay alive.

Max Q then E then W.
I feel that in the mid game Q is more useful than E as the attack speed is needed as you wont be building Berserker's Greaves. Yet after the two crit items all the attack speed will be fine.

Fleet Footwork is the best rune to go with as it gives more lane survivability and with overheal you are harder to kill. Plus with Celerity and Gathering Storm you will have more late game damage.

Tristana is a great champion to learn as Tristana can carry in the late game once you get through the laning phase. Obviously don't pick her into Jhin, Draven, Caitlyn, Lucian, Vayne or Varus. But, in all other lane matchups she can hold her own and do lots of damage.