I need to relearn some of the stuff in this book, but I highly recommend this book: Amazon.com: Super Memory - Super Student: How to Raise Your Grades in 30 Days (9780316532686): Harry Lorayne: Books

It has helped me a lot, but I need to get back into it and make it a life habit. It works for just about any subject you take, and has a chapter on several, including math. It's basically a technique to improve your memory, and it's not too expensive, so you don't risk losing a lot of money if you don't like it. I think the first few chapters are worth the price on their own.