It was a lot like the SAT. As someone else said it's computer adaptive, and later questions are both harder and worth more. That means you need to spend enough time on early questions that you're CERTAIN you aren't messing up, shooting yourself in the foot, and never able to see the harder, more valuable questions.
Buy a test prep book (Kaplan or Princeton) that has LOTS of practice exams (or questions) in it and do them. Over and over. You can train yourself to take the test, even if you can't study the exact material.
What you can and should study is MATH. I hadn't had a math course in years when i took the GRE and it showed. You need to relearn all of the shortcuts, rules, etc etc of the basic math you learned in middle and high school.
I studied, but am weak in math, and when the very first Math question came up it was a trick question, the solution was just multiplying the two numbers it gave you. I, however, sat there for a good ten minutes before I realized it was a trick question, and never was able to reach the higher level math questions. (That's why I scored 50th percentile math 98th percentile verbal)
I studied for a good solid month, a few days a week. If you're going to be spending the cash on the test, might as well do it right.