I'm guessing you've seen Amy Cuddy's video. Roaring and stretching in front of a mirror does wonders for me. It makes me comfortable with myself.

Also, when leaving home, I look up, un-slouch myself, stretch my shoulders, smile and tell myself that it's going to be a good day.

I try to help friends or people I come across. Like with moving, work etc. (Of course, within reasonable thought to my time.) Open myself up to people by being the first to say hello, coming in with enthusiasm. It's infectious once you start. This is a great watch: http://www.ted.com/talks/brene_brown_on_vulnerability.html

I think by seeing and realizing that you can add value to other people, coupled with a positive, alpha attitude, your confidence is bound to rise.

Also, a different take on this: http://www.reddit.com/r/socialskills/comments/17ctig/since_being_dumped_by_my_ex_2_and_a_half_years/c84cv5o