Hello, this is Starlux's guide to Caitlyn. I have been playing Caitlyn ever since I started League of Legends. My first match I did was with her and I went 10-2-13 normal game. Ever since then, I loved her. She has been my main for 9 months now. I would play her everytime I wanted some kills. And, I would get a LOT of them. So, here it is the guide I use for Caitlyn.

Good Things About Caitlyn
-She has one of the most longest range in the game.
-She has a stun (Yordle Snap Trap) and a slow (90 Calibur Net).
-She has a immense amount of damage.
-Her ultimate hunts those who have runned.
Bad Things About Caitlyn
-She is squishy
-Her ultimate can be blocked by other enemy players
-Her cooldowns are high in the beginning (You don't really need cooldowns later in the game).

My first item is: a Dorans Blade
Heading Back For The First Time I Usually Get: Boots of Speed if I am having a hard time with the people I am laned against. A B.f. Sword if I have a good amount of money and I'm having a easy time. Or another Dorans blade, if I have a low amount of money and want more ad and health.
My Main Build Is: A Bloodthirster for the life steal and damage(I always get a Bloodthirster first. ALWAYS.).
Then after the Bloodthirster I get my Beserkers Greaves which are good for the attack speed.
Then after my boots I get Phantom Dancers, which I love for the critical strike, the movement speed and the attack speed.
After Phantoms I get my Infinity Edge, which of course you know why.
After Infinity Edge I get my Last Whisper, which is good if a squishy person has a armor item against you.
My Last Item is usually a Banshees Veil, because it blocks 1 negative spell. Some other last items are:
A Thornmail for the 100 armor and for the returned damage
Another Bloodthirster if you are not being targeted and you want some more damage and life steal.
OR another phantoms (Which is good for backdooring because of the movement spped and attack speed)

My runes I think are the best for a Caitlyn, because at the end of the game you pretty much take away at least 400 health from the enemy with one basic attack. So I have the seal's and glyph's as attack speed so you can attack more quickly and kill more quickly. The mark I have as armor penetration. Armor penetration is good for those tanks and people with 1 defense item. Your runes combined with your last whisper ignore the players defense and continue on with your normal amount of damage.
For my quintessence I have strength which is good for that extra damage you need.

-For late game I would not use the Q move because it is useless, when you have all of your items all you have to do is use your basic attack.
-I would advise to stay in the back of your team so you can attack your enemies and they can't attack you.
-Always be moving, when you are moving it helps you dodge characters spells.
-Play aggressive. In the beginning aggressive is always a helpful factor. It helps you push and the enemy champion will become afraid to come close to you or your minions. (BUT, don't be aggressive if the other champion is, because that can result in a lot of deaths, trust me.)

Well, that is my guide. Comment for any questions or advice for me for the next update of my guide. Please vote yes if you like this, if not comment on something I missed. You can find me on the game as StarLux. I hope this helped!(: