How to improve positioning as AD Carry

Hi RofL,

I would like to improve my play as an AD carry so I can give more benefit to my team during ranked games.

I can last hit reasonably well and my laning is fairly efficient, but I have trouble finding a good spot where I can deal damage without getting focused.

What tips and tricks can you give in general, or champion specific (right now I'm working on Graves and Vayne) to improve positioning, both during laning and throughout the game to maximize damage and have a positive effect on the outcome of the game for my team.

Links to guides would be immensely helpful, but I would also like to hear your own personal opinions and experiences.

Thanks, gom gabbar