What happens if your parents say no you can't live with them for some reason?
Brother? Friend?

Okay, I see your point though, I'll answer properly, and without looking for loopholes in the question.
What I would do is look for a low level labor job of some sort. A kind where they provide you with shelter. (Don't care how bad it is) from there, just work my way up the ladder, save up, get cleaned up proper, get some professional looking clothes and immediately start applying for a slightly better position. I have a high school education already, and am fairly physically strong and dexterous, so I'd apply for maybe a police officer job or something. I think all it really requires is a GED and passing the physical test.
All this of course is temporary, and just so I can stabilise myself. From there, I'd start looking for jobs as high paying as my previous one. (I'm in medical school, so I'm assuming I'd be a doctor by then)