This is my guide on how to dominate the middle lane with Tristana.
The thing about Trist in the mid lane is that around the 10 minute you will become a one-shot killing god,BUT you also become very useless after your ult is down(your main damage source).
Also ready the whole guide to fully understand the champion and the role he is playing.

I really love playing with her in SoloQ,because people never expect to see an adc in the mid lane,which makes it safe to pick early.

Pros
You've got the spell with the most damage on level 1 in the game - Explosive shot
One of the best laners 1v1
Safe laning
You can use your Rocket jump to dodge ganks and 1v1's
She isn't a mana hungry champion,so the jungler can take the blue buff for himself

Cons
Once her W is down,she can easily be ganked in the next few seconds
Very squishy
Can kill just 1 targed
She becomes useless after her ult is down
Hard to farm with

When you lane you should always use your Explosive shot when your enemy is in range followed by an auto attack.
You can land 2 or 3 Explosive shot which will do around 50% of your enemy's health before you get to level 2 so when you get to level 2 all you have to do is land your Rocket jump on your enemy,use your Explosive shot and then your ignite.Your opponent will flash (and if he has heal he will use it) in panic,because he has either never laned agains an AP Trist or he is just scared on giving first blood.If by any means he survives on 50 or even lower hp you can use your flash to auto attack him and get 1th blood.
When you're fighting an objective,always make sure NOT to use any spells on it except your Rapid Fire in case an enemy shows up.
In teamfights,you have to focus on jumping on the adc or whoever is fed the most and burst him down and then jump away while the enemy team just finds out what happend.
If Tristana gets fed,she can DESTROY a certain enemy NOT their whole team,so that means she cannot carry games in terms of teamfighting.