Usually, I prefer to draw/create things from my imagination. When I get in a slump creatively, though, I find it helps a LOT to start drawing from real life. I'll go find something interesting to sketch, or if I'm really lazy, I'll find a picture of something interesting online and sketch that. (My favorite source for reference images is this:
http://www.google....ages?q=ugly+people . I know it's mean, but they're so fun to draw!)