Schedule your GRE time slot for your best time of day. If you are slow to get your day started, schedule the exam for mid-afternoon. If you are a morning person, sign up for an earlier time slot.
Block off enough time in your test day's schedule for the GRE. The GRE typically takes 4.5 hours to complete. This completion time does not include your sign-in time or any break times in between sections.
Memorize the directions for the different GRE sections and question types. This will allow you to spend your time answering questions rather than reading directions.
Get a good night's sleep. Feeling well rested on your GRE test day will reduce your stress level and help you feel more confident.
Plan to take a break after the tutorial section before you start the actual test. Go to the restroom, eat a quick snack or just stretch to relieve any tension.