What do girls look for and what do I have to change for girls to notice me and take me seriously?

I've always been the clown. I'm the guy that always made the jokes, made people laugh. I have a crappy labor job and I think between that and my personality I can't get girls to take me seriously. I'm a little overweight too. Not much. I'd say 20lbs. The thing is I want to settle down and get into a serious relationship.

What do girls look for and what do I have to change for girls to notice me?