I would HIGHLY recommend that you purchase the ATI practice exams, there is a version A & B. I bought both, but would buy at LEAST one of them if I were you. I took one version about 3 weeks before the exam and the second one about a week before. It allows you to time yourself as you would be timed on the exam (you need to time YOURSELF manually, the software doesn't do this for you which is quite annoying). It gives you practice answering questions on the computer screen, and using the on screen calculator.
I didn't use the ATI manual, but I DID use Mometrix TEAS, TEAS Mastery App and Pocket Prep TEAS. I think the apps helped me a lot simply because I'm always on the go and working, so it helped me get my studies in when I had time. The Mometrix book has three tests in the back and detailed explanations of each question which I really liked.
I scored a 90. For what it's worth, I'm very good at math (I work in finance) and found the reading section pretty easy. The key to your studies will be reviewing everything, but focusing heavily on where you struggle.
Edit: When you do the practice exams in your book, I would do them on a separate sheet of paper. Depending how much time you have, you may want to retake a test more than once. Given enough time, I generally forget exact answers so it was still useful to repeat the tests. You can probably also more easily sell your book