Curious when you suggest you start the GRE - how many months in advance?
I just took the GRE this past December 8th, and I agree with Colette. I only had a month to prepare, so I made studying the prep books my 8 hour a day job. For best results, try to work on it about 8 hours a week for 3 months. You'll get a perfect score. And buy a test prep vocabulary book with at least 800 words, make flash cards, and memorize every one. Try to get them all memorized early in your prep period. As mentioned above, make sure you download the free GRE prep program that you receive upon registering for the GRE. They give you 3 tests for free that are extremely similar to the ones on test day. I would save these for your last 3 prep tests before the big day. (Those last 3 should span 3 weeks. Try to take the prep tests on the same day the real test will be.)
Let me know if you have any questions.