First, I would like to say this is my first build and I am by no means an expert player, but I do want to ask everyone to try the build before they down vote it. I find that she doesn't need a lot of survivability items until late game because she has some of the best escape mechanisms of any ranged carry besides Tristana.

Pros
-Excellent damage
-Awesome laning presence
-Great harassing tools
-Not as squishy as she looks

Cons
-Mana hungry early game
-Needs CC on her team

I love me some red Armor Pen runes for the early damage and CD reduction runes makes Piltover a little spammable. You could easily take Attack Speed runes if you like, but I feel she doesn't need it after items. With the new patch, Clarity runes may not be as needed, but I still like them.

I almost always get my items in the order listed above, as I find this blends damage with AS just right to always be dishing out the most that I can at any given level. For those that haven't noticed, I leave the item build at just damage items, this is because I feel that what survivability item I do get depends entirely on the enemy team composition. For nukers, I take Banshee's Veil, for magic heavy teams, I take Force of Nature, for physical heavy teams I like taking Randuin's Omen.

I take Ghost for the quick get aways and Clairvoyance for awesome snipes with Piltover Peacemaker and my ultimate. I don't like Exhaust and Ignite because their range is actually shorter than Caitlyn's auto-attack range, which causes problems. The only other spells I would consider are Flash and Clarity.

Suggestions are welcome! I hope you guys like the guide, I feel like you should play every champ in your own style, but I think this item composition makes her downright hard to deal with. Dropping a undodgeable 1k+ nuke in the late game is rough. Despite the gimmick of taking the bullet for someone, it still HURTS. If you like it, upvote! If not, tell me why!