You won't be permitted to take the test unless you have one acceptable form of photo identification with you. A driver's license, passport I.D., or student I.D. will suffice. Although the official GRE Bulletin indicates that you should have two forms of photo I.D., don't worry you'll only need one. To help ensure that nobody else takes any part of the exam in your place, the exam supervisor will also take a digital photograph of you. DO consider requesting earplugs for the exam.
Earplugs are available from the exam supervisor upon request.
I suggest you wear earplugs. Expect the supervisor to escort other test-takers in and out of the room during your test and to converse with them while doing so. If the testing room is busy, expect to hear lots of mouse-clicking during your test. DO know the location of the nearest restroom. Be sure you find out before you start the test where the nearest restroom is located.