If you don't already have it, get yourself a copy of the CLEP Official Study Guide. And since you want to take College Mathematics, you should also get the Princeton Review Cracking the CLEP. You can find both of these at Amazon.com, and they should cost you around $30 for the pair. Read the review material, especially in the Princeton Review book, take the Princeton Review practice exam, go through all the answers, especially the ones you got wrong (but review the ones you got right too -- it's good practice), then take a break. Next, take the practice exam in the Official Guide. If your raw score is over 60% (some will say 50%, but I like to have more "cushion") then you are ready to take the real exam. If not, go through the review steps again, or come back here for more advice.