The Compass computer-adaptive test is a placement test designed for colleges to be able to place students in appropriate courses. For example, a low score on a Compass test may mean that you have to take remedial math classes before taking classes for credit. Because college classes cost money, placing as high in the course ladder as possible will ensure that you don’t spend unnecessary cash on non-credit classes.
Look at the Compass site for sample problems. Practice with these to give yourself an idea of what to expect on the actual exam.
Review your high school algebra, geometry and trigonometry text books, as they cover similar material to the Compass test.
Visit your campus math tutoring lab if you are having trouble with a particular type of problem or area of math. The tutors there have passed the classes you’re trying to get into, so they will know what you should focus on.
You cannot buy a textbook that will adequately prepare you because the test is designed to determine how much you've learned over your entire school career. They don't hone in on a specific area, it's very general.