I learned a long time ago that - at least for myself - the very best way to edit one's own work is to read it to oneself *out loud*. Of course this doesn't guarantee a perfect edit, but it does force the writer to see each word as he says it, instead of skimming past it because he already knows what he wrote there.

That being said, I've also learned to treasure having a good editor. They are worth every bit of the hassle and humiliation of watching one's hard (and heartfelt) work sliced, diced, and julienne-fried before one's eyes.