While preparing for the test: Definitely use Shaggy's method. I used the same method, but with multi-colored sticky labels (one end is clear tape which you stick to the book; the other end is colored and non-stick and sticks out so you can see what you labeled). Because I did not want to spend too much time tabbing, as I practiced problems, I did not color code. Also, some of the topics overlapped so color-coding would have been tricky (but that's just me). Also, the tabs I had were wide. So, I cut them in half and wrote smaller (but clearly) so that I would have enough spacing between tabs, especially on my thinner books.
Take to the test: I took two rulers and a green plastic slide-edge (the kind used in drafting classes, with the cut-out circles and shapes). I took only two rulers and one straight-edge, because I found that three were the most I used while I practiced problems. As you practice problems, you'll find out what amount is right for you.
During the test: Right before the test started, I requested an extra pencil. This was to make sure I did not run out of lead, and have to raise my hand, and waste time waiting for another one during the test. I did not run out of lead, but it gave me peace of mind, and I used that extra pencil as a bookmark.