In my opinion Tristana is one of the more underrated champions in League of Legends. That being said, some people will disagree with me and others might not.

Tristana is a versatile champion in game. Depending on the situation, she can be a powerful AD Champion or a powerful AP champion. Unfortunately, she is a glass cannon. On a side note, she is ranged, meaning if you are careful, you will not be killed.

9x Greater Mark of Magic Penetration Gives you 8.66 Magic Penetration to start with. If they have no magic resist, you do bonus damage.

9x Greater Seal of Vitality Gives you 9.72 Health to start. In my opinion, more health is better, but if you would rather, getting 9x Greater Seal of Armor would work too.

9x Greater Glyph of Scaling Magic Resist I prefer getting magic resist than cooldowns on glyphs. The reason for this, is because most of the time I am going against an AP caster or ranged AP. The more magic resist I have, the less likely I am to be harassed.

3x Greater Quintessence of Scaling Ability Power is what I prefer to use. Tristana has decent cooldowns, but if all skills are on cooldown, you aren't harassing. I usually auto attack creeps anyway.

3x Greater Quintessense of Swiftness is a viable option if you would rather get an AP item to start.

I followed the AP line down the offensive tree. The more AP you can squeeze onto Tristana, the more burst damage you can do at a time. I try to keep her away from enemies as much as possible, so I went down the utility line for the 9. Movement speed is a great factor for Tristana, the better your movement, the easier it is to line her up for a gank.

With her full build, she can do 2,351 damage with all of her skills. I can send a full rotation of skills off in about 2 seconds if they aren't bunched together. This turns her into an assassin vs many carries.