Just coming back from the AOTA conference in Long Beach, CA, without a doubt, people told me to buy the NBCOTexam.com study guide. It's cheap and has a lot of info, plus the practice questions are supposed to be really good. I got a $2.00 off code that didn't work but supposedly there is one out there that get's you $2.00 off. Ask around the OT forums but if not, it's only $24.95 which is so much cheaper than anything else out there. I hope that helps...