Here is the advice from previous students and others about taking the General GRE
A) Allow an extra half hour getting there on exam day, even if this means you have to get up pretty early. You really don't want to be stressing out about traffic delays and parking just before your exam.
B) Wear cool clothing, perhaps with an overshirt you can take off. It is really hot in the exam room, and this caused a previous student to pass out during the exam.
C) Make sure you’ve eaten and are properly hydrated going into the exam. “You may not have any form of food or drink in the testing area, though you can have access to this during your break or any time you leave while the time continues.”
D) “You may also not bring in objects that can transmit or store voice or text, such as cell phones, pagers, PDAs, etc.” http://en.wikibooks.org/wiki/GRE/About_the_TestE) “On Test Day arrive 30 minutes early to complete any paperwork. If you arrive late, you may not be admitted and will not be refunded.” http://en.wikibooks.org/wiki/GRE/About_the_Test
F) “Bring identification to the test center. “ http://en.wikibooks.org/wiki/GRE/About_the_Test
G) “Unofficial scores appear on the computer screen following your test. Official scores are mailed to you and the institutions you choose 10 days to two weeks afterward.” http://en.wikibooks.org/wiki/GRE/About_the_Test
H) You have the opportunity to discard your scores if you feel you've done poorly, but you don't get to see your scores before you make your decision. If you discard them, there is no record on your official report of your having taken the test at all. The disadvantages are the extra time and money it costs you to take the exam again. My opinion is that, if you think you've done reasonably well on the math part, then you should accept your score. However, if you know things have gone poorly on any section, and you think there's a good chance you could do better on a second try, then go ahead and discard the scores.