I saw a T-shirt that said, WHAT I IF TOLD YOU YOU READ THIS WRONG?
See how easy it is to miss typos and other errors? The best way I know to catch these glitches is to read out loud and slowly. Really, really slowly. One word at a time. If you read backwards, you will catch blatant spelling errors (but so will your spellcheck software); however, you won’t pick up missing words or inadvertent spelling mistakes (e.g., typing were for where, you for your).
As for reading out loud, you don’t have to use a stentorian voice and startle everyone else in your office or neighborhood. As long as you can hear your voice come out your mouth and go into your ears, that will do.
When we read silently and at our normal speed, we read what we think we wrote, not what we really did write. And sometimes what we really did write can be embarrassing. It’s worth your time to proofread carefully.