While editing your ms for typos, print it out (because you always catch more mistakes on hardcopy than on a computer screen) and read it from right to left, rather than left to right.
Supposedly, since this is the opposite of what your eyes and mind are trained to do when reading, you should catch more of the typos you wouldn't catch when reading normally.
This made sense to me. I know that when I'm reading my own work, my mind will sometimes read the text as I know it's supposed to read instead of how it's actually printed.
The other tip was to print your ms out in an entirely different format and font from what you've been working in.
The reasoning behind this is your ms will look entirely different from what you're used to seeing, and as a result, will make it easier for you to catch mistakes.
I don't know if either of these tips actually work, but in preparation for my submission of IH next month, I'm going to try both today and see what happens.