freelance?

anyone have any advice about freelance writing/editing? i know there are some chicago publications (the reader, new city, red eye, etc) that accept articles, but i never know where to start on things like that. i'd rather have some sort of guideline or assignment. or better yet, editing and proofreading. i try looking on craigslist and other things like that, but so far nothing i've responded to has panned out. 

advice? anyone successful with this?