- Find a copy of a reasonably current Princeton Review "Cracking the GMAT". Your local library is likely to have one. Focus on the math review and the test strategies, not the sample problems. Vital math topics to review include exponents, basic geometry, probability (memorize the permutation and combination formulas), factoring, and prime numbers. The GMAT tests prime numbers frequently.
- Visit GMAT Hacks and read as much as you can. There are tons of wonderful articles. including one personal favorite that lays out this 'overlapping sets' formula: Total = Group1 + Group2 - Both + Neither
- Do as much of the 'official, real GMAT problems' book as you can. As you go through the problems make sure to mark all them that you weren't sure about as well as all the ones that you missed... and re-do all of them.
After I did all of this, I took the exam and fell just short of my goal. I did a lot of studying in a tight time period of 6-8 weeks and allowed another 4-5 weeks for a re-take. I worked heavily with a 'more official math problems book' as I geared up to re-take the test. Additionally, I borrowed math books by the Manhattan Institute from a friend which were great last minute supplements, particularly with difficult problems, as preparation for my second attempt.