I took the AFOQT 2 years ago. I just went to the public library and checked out some of the prep books they had there.

Be up to snuff on doing math by hand; no calculators allowed. Practice the block counting, shape rotation, and chart reading tests. Being familiar with those before taking the actual test helped me a lot.

If I remember correctly, everything else is your typical standardized test stuff; grammar, reading comprehension, science/math, etc.

Oh, and the aviation knowledge questions are practically straight out of the private pilot knowledge test bank. If you're at least a private pilot, you don't have much excuse to not ace the aviation knowledge test section.

Good luck.