So where do you start? You have several options. You can sign up for a GMAT prep course and get a head-start on getting used to being back in the classroom. These classes can get pricey though, so keep that in mind.
A visit to your local bookstore will turn up a slew of review books. I bought The Princeton Review's Cracking the GMAT, and it didn't steer me wrong. Not only does it include myriad practice questions (along with explanations of their answers), but it offers a rather extensive review and a great tutorial for tackling the essay questions.
Don't neglect online resources. In addition to searching Amazon.com for recommended review books, I also found some reviews online. I bookmarked the Test Prep Review Web site and tried to block out some time every day to work through some of the questions. I liked this Web site because it divides reviews up by topics, so I could concentrate on algebra for one day and grammar another. The site also boasts "improvement links" to help you review some of those long-forgotten concepts.
Hands down, the best resource for both my husband and me was the test prep software from MBA.com, which you can download for free after registering for the test. The practice test is exactly what you'll see on test day, and it gives you the chance to familiarize yourself with the computerized exam.
Regardless of which ones you choose, your best resource is time. The GMAT covers an extensive array of subject matter, and last-minute cramming isn't going to cut it out if you've been out of school for a while.
Begin with a practice exam to get an idea of which areas you need to concentrate on most. Most important, come up with some sort of schedule for studying and review. And then, hit the books. It's good practice for earning your MBA!