Allow yourself enough time to study. Take advantage of GMAT preparation courses and study materials. (See Resources.) If you are having trouble motivating yourself, ask a friend to study with you. The GMAT is a formidable test. You will do yourself no favors by leaving studying to the last minute.
Take GMAT practice tests. (See Resources.) This is a good way both to familiarize yourself with the structure of the GMAT and to find out in which areas you are in need of improvement.
Take care of yourself. Get a good night's rest and eat a substantial breakfast. Going into the GMAT with a clear head will increase your chances of success.
Give the first questions on the Verbal and Quantitative sections particular care. The GMAT is computer-based and automatically adjusts its difficulty level depending on how you answered the previous question. For example, if you answer a moderately difficult question correctly, a more challenging question will be presented afterward. This affects your score by gauging your competency level in a certain section. The more difficult questions you answer correctly, the higher your score may be.
Answer every question. You will be penalized if you skip one. When in doubt, take an educated guess. If you can eliminate a few incorrect answers, you will improve your chances of hitting upon the correct one. Remember that you cannot go back to a question once you have answered it.
Pace yourself, but do not linger too long on each question. You will not be given any additional time to finish each section beyond that allotted. Failure to complete the GMAT will result in a penalty.