I'm addicted to rewriting. Like the great Connie Willis, who claims she rewrites grocery lists, I revise and revise and revise until the words on the page stop making sense. There's an old story about Japanese wood carvers that says they will continue to carve on a sculpture until someone takes it away from them; I've always thought deadlines serve that purpose for me.
I also read my work aloud. When a passage feels odd, or clunky, or tortured, I sit at my desk and read it out loud to myself. Usually this will expose whatever's not working--and it usually means some precious word has to go.
There's a wonderful little book by a clever man named Ken Rand, and published by Fairwood Press. It's called The 10% Solution, and it's the best handbook for rewriting I've ever found. Rand bases his system on his experience as a newspaperman, and its principles make great guidelines for self-editing.
I'm in the revision process now for my work-in-progress. Fortunately, my agent has set a deadline, because he's forcing me to be organized. Otherwise, I would be going over every page with a magnifying glass, finding that single word that's out of place, that metaphor that doesn't quite click, that simile that . . . well, you know. I'm just lucky someone will take this thing away from me before I polish it to nothing!