my name is Lolz4life25 and this guide is for Caitlyn. I like to keep my guides short as possible with all the needed information.

The runes are quite simple for any AD Carry. As normal, go for armor pen runes, attack damage glyphs and attack damage quintessences. For the seals you have either 3-4 choices. Either go for attack damage seals which is recommended if you love easy last hits. Crit seals could help late game with your passive hitting. Attack speed seals could help for an early lead and if you are playing aggressive on your lane. life steal and armor seals could help if you are new to Caitlyn but i do not recommend it to the play style.

Not much to explain with these. The basic AD masteries are used.

Start off with boots and three health pots because you need to stay in lane as much as possible. your first recall should be either when you can afford 2 Dorans Blades or if you can afford your B.F Sword. The point of rushing the B.F Sword is for the Black Cleaver.
The Black Cleaver is for the attack speed and the almost true damage on the enemy ADC. This item can also make it easier for pushing your lane and at the same time getting those last hits.
After that item you will need Berserker's Greaves. Buy these as early as possible; you need that attack speed and movement speed to get back in your lane.
The passive on Caitlyn is special to the IE for yet you will be Criting like a boss after this. The IE is there for your passive the most. If you like to roam the jungle, this item is something you will need to rush because you passive procs faster whilst in brush.
If you think you crits are not coming along as much as you expected, get a Zeal for movement speed and attack speed. this also gives you crit chance for you passive.
The next item would of course be The Blood Thirster. This is extremely important for any ADC. charge this item up and you will be an ultimate 1v1 champ.(maybe 1v3)
After the Bloodthirster you will either have different choices on what items you will need depending on your play style. I personally chose the Frozen Mallet because then they will be unable to run from you.
Finnish the build off with a Phantom Dancer. Don't you worry about finishing your build, you will be done by then.

I had no idea what i was doing but i'm pretty sure this will guide you. your Q is your long range poke but i'd go for your W first for an easy first blood hiding in the bottom brush.

Do i even have to explain this? o.O

I think that i have explained this in the items section; but not like you will read it. All you need to do is stay in lane as long as possible (DO NOT PUSH). The reason why you don't push is for your own good. You can push, i'm not saying you can't but i like to hold my lane close to my turret so that your enemy's lane is helpless to last hit. Keep in mind that you are mana hungry and that if you like to harass with cait more than anything, I'd recommend someone on the lines of Saroka. She is slow but her silence and healing capabilities are amazing after 5-10 minutes.

When playing early game, try to hold your lane closest to your turret. The reason i say this is because your perfect laning pal is Blitzcrank. Put your yordle snap trap downand let Blitz stand just behind it. once he pulls one in, the turret will attack, your snap trap will detonate and the rest is up to you. This is if you want to play safe on your turret and not go in the brush early game.
Another skill is simple. When in the tight spot and you know you're going to die; Just E over a wall and you should have no need to waste flash. Careful not E through think walls because your E has a shorter distance than your flash. use your flash as a backup or for awesome DUKES!
A useful tip on a W and E combo. The enemy lane is bound to step on your traps. place one on the very edge of the brush towards their side (they can see it that way). once they step on it, Q them ASAP. once that is done, use blitz to pull him/her in on another trap of yours (assuming you have blitz) and another kill is just for you.
When in mid lane (which is actually the best) your ult is perfect for yet no one is there to intercept it making an easy kill easier.

Please send in pics on how your stats were. This helps me add onto the guide (videos help too). I'm planning on making a team guide with this Caitlyn because of the Blitz assistance. Also tell me what to add depending on your play style. I am willing to try new ways on building Cait. I can attempt your requesting builds on any champ possible.