Richard Nordquist provides ten short tips for proofreading in an article at About.com. Blink and you might miss them.
Here We Go
If you have time to step away from writing before proofreading it, use it. Look for one type of problem at a time. Recheck all your facts and name spellings. Review a hard copy to get a fresh perspective. Read it aloud. Use a spellchecker (duh), and use a dictionary to ensure that you used the right word (“raise” versus “raze,” etc.). Reading text backward will catch typos. Make a list of the typos you make most often so you can better look out for them. Lastly, recruit a friend to help; threaten if necessary.
You can read the full article here: http://grammar.about.com/od/improveyourwriting/a/tipsproofreading.htm