DailyWritingTips.com, one of my favorite blogs, did a recent summary of proofreading tips and techniques. They are all excellent. I particularly like a few:
Put it on Paper
I have a nice monitor in my office. I know how to fill the screen with text but I still miss errors when proofreading on the screen. I always print out a draft and move away from the computer with a highlighter and my trusty red pen. Just make sure to recycle the paper from your drafts.
Have Someone Else Read It
I often recruit others to read my work as it nears completion. A lot of times I know in my head what I meant to say and, as a result, I completely pass over the fact that I didn't actually write what I was thinking.
A Half Tip From David...
One tip I'd like to add to the list is to avoid procrastination if at all possible. If you finish your draft early, you then have the luxury to put it down and come back to proofread it the next day. It is amazing the mistakes I've found when putting some time between generating drafts and proofreading them.
Check out the full article here.