Get plenty of practice behind the wheel. Some states, such as California, require that first-time drivers have at least 50 hours of practice time behind the wheel with their learner's permits before testing. You should have plenty of real-world experience before attempting to test for your license. Maintaining speed, proper signaling, construction zone protocol and parallel parking are a few of the major tasks. It's important to take it seriously and not consider your practice a joyride; have your accompanying passenger critique your performance.
Take practice tests. Many jurisdictions have booklets that offer them, as do most driving schools. Also, there are a great many of sample exams on the Internet as well. When practicing, don't cheat and peek at the answers; you want to accurately simulate the testing scenario. If you search online, focus on your own state's laws.
Have your friends quiz you. It's one thing to sit in your easy chair and fill out answers in a booklet, and another to be in front of a computer answering practice questions. You'll do yourself a favor, however, if you are asked to recall information off of the top of your head. Give a friend or family member a practice driving test with the answers and have them ask you the questions in random order.
Ask your friends and acquaintances who have taken the test what to expect. You have presumably prepared yourself to the best of your abilities, but it can help to know if there are any curve balls to expect. For example, are there any particularly rigid examiners at the DMV to look out for? Also, much of the test may simply focus on just a few key sections of your study booklet.