I recently scored a 99 on the ASVAB, and wanted to share a warning for test prep...As far as study guides go, ARCO is the standard and probably for good reason. I would watch out for The Princeton Review... They put out a pretty thick guide with several practice tests and instruction sections. However, I took note of several blatantly WRONG answers in both the instruction and practice sections throughout the book. If you're really confident, buy the book and see if you can spot the wrong answers for extra practice and confidence building, but for anyone who wants to seriously study and imporve their score, I wouldn't recomend The Princeton Review.