This is my build for a hybrid Tristana.

Pros:
Your abilties will hit like a truck, Tristana has really nice underused AP ratios.
No mana issuses.

Cons:
You dont have crazy fast auto attacks that instantly rape face like a regular AD Attack Speed build, but your auto attacks still hit really hard.
Still a squishy.

Armor Pen Marks = no explanation needed.
Health Regen Per Level Seals = Help's her lanning phase.
Mana Per level Glyphs & Quints = To further improve the effect of Manamune and Archangels.

Tristana has good AP ratio's so the masteries are designed around furthering the amount of mana she has and having her get more ap, along with improving her AD damage since this is a hybrid build.

Exhaust & Ghost = They both have the capability to be used equally for offensive and defensive purposes, and being a pain in the *** to catch while running away as tristana is always nice.

These item's dont HAVE to be bought in any particular order. You can start with boots and if your solo top lane and live long enough to afford guinsoo's rageblade, then just buy it. if not, then get a tear's and a manamune first off, followed by an archangel's. You want those boots of mobility though because tristana is slow and the boots allow you alot better map coverage.