Kaplan has a saying, "if you don't change how you take the test, you won't change your score".

You need to understand what mistakes you are making and why. Are you reading problems incorrectly? Do you not know the material? Are you making careless errors? Are you mixing up signs?

Try putting together an error log that identifies exactly why you missed each problem. Look for trends. You will never see any of your practice problems on the actual test. You need to learn the content and the strategies. By thoroughly analyzing your own mistakes you can identify changes in your approach. By correcting a trend, you correct several problems, making quantitative jumps in your score.

Don't overlook the questions you answer correctly. First, note those questions you were unsure of or guessed on a practice test. Too many people guess because they don't know the answer for sure. If they get lucky and guess correctly they never understand how to get to the true answer. You can't rely on correct guesses on test day. Examining your correct answers also helps you understand what you are doing right so that you can duplicate that on test day.

You may find that a good strategy-based prep course, such as Kaplan's, (available online anywhere) will help you learn the correct approach to the test. An experienced tutor can also help you identify consistent errors that are interfering with your score.

Just taking practice tests without analyzing and understanding your performance is a waste of time. It is like practicing target shooting with your eyes closed. If you don't clearly understand what you are doing wrong and what you are doing right, you cannot consistently score at the level you desire.

Good luck,