Caitlyn is a very strong carry, with the ability to harass early game and tear through squishy and high armour targets without being touched if played right.

Pros:
- Great harasser
- Her Q has awesome power early game
- Good farmer if Q is used right
- Can perma slow at awesome range
- Range is awesome on auto attacks and skills
- Great kiting champ
- great passive

Cons:
- Squishy early game
- Item dependant
- auto attacks weak early game

The way I play Caitlyn, I like to abuse her range with armour pen, but like ashe she runs out of mana really quick which can stop you harassing enemy champions in the laning stage. So I like to run armour pen marks and quints with seals and glyths on mana regen.

Masteries I use 21-9-0.

simple really gives great increase in damage and gives some armour and magic resistance which she really does need.

Oh items, now it gets more fun ;)

I start with a doran's blade due to its +100hp and lifesteal and +8 damage, which makes you less squishy early game, gives you more damage early game and gives you health back to lane for longer. also start with a heath potion. Asap built boots.

next you need to build a bruitalizer, this will give you a massive boost in Amour pen and give you a 10% CD.

depending on how you've been fed build either a giants belt or a recurve bow. I personally like to get my frozen mallet first to stop me from dying quickly and it lets me chase more. If u want you can rush a mandred's bloodrazor to just rip people apart. If you do get blood razor first get frozen mallet next or vise versa.

Now go for a Blood thirster and farm like crazy you need the +40 damage, overall you will have more damage that a IE and be gaining so much health back from it in fights. Best way to farm minions in laning is to get them all in a line and fire your Q straight through them all, yes your damage decreases but you'll be doing so much damage to them you'll probably kill alot first.

Next is a phantom dancer or a starks this is really personal preference I switch between both all the time, phantom dancer gives you that bit extra chase and attack speed but starks gives your team that extra bonus and life steal and health regen so it's up to you.

situational items are the banshee's veil and the black cleaver. banshee's if the enemy team is caster heavy and the black clever if their team is tank heavy.

you have to built your Q as fast as possible putting points into your ulti as you go. in the recent patch these both got buffed. your best escape is your E which you should also put points into. I find at level 3 you should have at 1 point in every skill apart from your ulti obvs ;).

I use flash and ghost personally just for the extra chase/escape it also makes having red pill and frozen mallet awesome.

Always grab a red buff with frozen mallet its overkill slow. with your range they will never be out of range.

in team fights NEVER lead with your ulti its a waste, use it to kill strays and abuse your Q and W. Fire your Q at the enemy team even with the damage falloff you will still hurt them. and dropping your W into their escape routes before they take them will insure for a easy kill.

Well i hope this helps i'll update this as patches come and go. hopefully she'll get some more love from riot ;)