I admit, I am the worst proofreader on the planet. OK let me clarify, I cannot proofread my own work, God bless me... I can see someone else's mistake a from across the room. I used to think it was my poor vision, but that wouldn't explain how I could only find OPMs (Other People's Mistakes) now would it?
I found a really terrific article with lots of good advice, great links and even some practical reader comments to help you (and me) become better proofreaders. Its true a computer cannot proofread -- only a human can!
http://writetodone.com/2010/12/04/get-your-eagle-eye-on-10-tips-for-proofreading-your-own-work/