Welcome to my first build, Caitlyn :)
since this is my first build here it wont have so much information but i would LOVE many comments ( not cruel but helping ) anyways enjoy :)

now as first i would recomand you go MID with caitlyn for farming and to lvl fast, and the reaspn you should Lvl Piltover fast is because its a GREAT way to push a oppoment back and get thair minions killed fast.

it is important that you make sure your team will support you at any time while your mid, since it can be tricky to get caitlyn away on the right times, and more important is that you go help your team mates and i recommand you help them by hideing in the bushes and attack the oppoment when it is needed most.

and now for SNAP TRAP.
you should always place it in the 2 bushes on the right and left in the mid incase the other oppoments are sneaking in on you, and when you get to around lvl 7 go place one infront of the boss monster, then your team will know when they are there and you can all rush over there to get them piled down. and its important to have a good cooldown to use this as quick as possible.

90 CALIBER NEW
as you all know its a perfect way to escape, either shoot it at a champion behind you to slow him and get a little ahead while running, or you can use it to get over small walls and so on.
DONT use it while your pushing, but if you have tryed caitlyn you already noticed that.

last but not least ACE IN A HOLE.
when a champion is hideing at thair tower with low health its a GREAT skill to snipe them down before the go back to thair base, also a great pushing skill since the oppoment will run back to thair tower when they see the red ring under them.
use this skill carefully because you will never know when you will need it.