Skin breakouts: How to stop and prevent them?

I drink lots of water and take a multivitamin everyday but my skin still breaks out (not too severly though) sometimes. I'm a 19 year old female. I'm thinking it could be cause of stress, but I can't really help that too much. Lately though, I've been getting a breakout on my back and a little on my chest. I've been using my face wash on those places to try and make them go away. Will that help? What can I do to help clear up my skin? By the way, I'm using a clinique skin care line.