Tips for Caitlyn?

So I recently bought Caitlyn. And I must say she is really good. However, she is a harder to control. Early in the game I am able to attack the enemy champions with ease and I am able to prevent them from advancing towards the turrets. However, in the mid game as well as in the late game, I am not able to do a lot of damage. Usually I score around 3-4 kills. That isn't really bad as I don't die a lot as well, but I want to score more. Any tips are appreciated.

P.S. This is not the account that I use. I have an NA account. But for some reason I am unable to create any sort of discussion on it. I created that account a few months ago and I have reached level 9 on that. Any idea why that is happening?