The key is setting up a study schedule and sticking to it. Leave yourself at least one day a week and a little bit of time each day to enjoy life and get away from studying. I liked dividing up my day between questions in the AM and reading in the PM. I used Kaplan's Q Bank for questions. It was very helpful not only for learning (read the explanations, especially if you missed the question), but also directing your reading focus. You will be able to identify strengths and weaknesses you need to spend extra time on.
I recommend starting out doing random subjects in 50 question blocks to get used the testing format. You can hone in on weaknesses once you identify them. Path and Physio are the hardest hit subject areas, so definitely spend some extra time on these in terms of days studying, questions, and materials used (I used BRS). High yields are a good brief review for less stressed material such as Immuno, Behavioral, Anatomy, and Genetics. Use what works for you for Micro and Pharm as everyone has different styles. Anywhere from 4-6 weeks is a good amount of time for preparing. If you go much longer than that it is easy to lose focus. Most people know when they "feel ready" to take the exam.
Study hard and good luck!
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Alpha Omega Alpha
http://www2.uic.edu/stud_orgs/hon/aoa/