Re-familiarize yourself with the format. Try to recall the different parts of the test and how they made you feel. Determine which sections were a struggle for you and whether you struggled because of the content or the setup of the test. This analysis allows you to focus on areas where you need more work. Also, unlike other standardized tests, the COMPASS test is not rated on a pass/fail basis. Instead, the scores show which areas you are strong in and which you need improvement on, so use the rankings in your result report to guide your studying.
Work through sample problems. Remember that the COMPASS Math Test is not timed, so as you work through the sample problems, do not rush. Take note of the types of problems that give you trouble, so you can go back and gain a better understanding of them later. General math tutorial sites are helpful, but for COMPASS test sample questions try sites such as the official ACT website (act.org) under the COMPASS test section or sites made specifically for COMPASS test questions like Compass-Test-Questions.com.
Consider hiring a tutor. Bring the trouble areas to your tutor and you will receive a fresh perspective on how to strengthen your work.
Give yourself practice tests simulating a real testing environment on the computer. Working out the problems on paper is one thing, but including the extra step of entering the answers onto a computer screen will help. Create a quiet testing area and go through the entire test as if it were the real thing. Full practice tests can be found at CompassTestQuestions.com and Compass-Test-Practice.com.