Look for a GRE practice prep book that contains high-quality material from a top publisher that is reputable and has several decades of experience in the industry to ensure the content is accurate and current. The top prep books cover each section of the exam extensively and offer strategies for answering multiple-choice questions or writing the two essays in the writing assessment section. The top GRE practice prep books include online practice tests that can be retaken multiple times and mimic the real GRE test that is taken at a testing center.
The type of GRE practice prep book that you obtain should also be influenced by multiple factors like the amount of time that you have until your test date. Certain sections that you may need to improve your score in are an additional factor to consider because some books focus more on certain topics than others.