
Chris T. answered 04/15/19
SAT & GRE Tutor, ready to demystify the tests for you
ETS has a lot of resources available on their website, including two free full online practice tests and their entire pool of essay topics. The online tests are more useful than paper ones, as you'll prob be taking the real test online, so you'll want to simulate test conditions. As for other free resources, your library likely has GRE prep books, though they can be of varying quality. Always try for official ETS material if you can.
One thing to be very careful of with the GRE is that the questions are extremely tricky, and studying on your own you may be susceptible to falling into traps. I'd recommend using an experienced GRE tutor for at least part of your study, someone who can explain how the test works and help you develop good habits that you can then practice on your own.