Learn about the test. Learning about the GRE will help you prepare for it because you will know what to expect on test day. Purchase a good GRE book. I found "Cracking the GRE," published by The Princeton Review especially helpful, but there are several good books on the market.
Learn vocabulary. It is impossible to learn all of the words the GRE might put on the test, so it is best to learn the meanings of different prefixes and suffixes.
Review high school math. The GRE contains high school math problems, such as algebra and geometry. Memorize formulas for algebra and geometry.
Learn how to write argument and issue essays.Many GRE books will provide tips on how to write good essays for the test. Review the tips and practice writing essays in the amount of time the GRE will provide you: 45 minutes for an issue essay and 30 minutes for an argument essay.
Practice the types of questions the GRE will have on it either in a GRE book or on a web-based practice test.