I would say to not time yourself the first time through. I would look at each question and reason through each answer. Even if you know which answer is correct, know why the others are wrong. That's what I did, and it's worked pretty well so far. I'd do a chunk of questions and mark the ones that had choices I wanted to look over. Then I'd check them and go to a textbook if I needed more info. Look at it more as a study guide than a practice test. Once you've gone through it and want to go through it again, timing yourself might be a good idea to get used to having a clock running.