I started studying for Step 1 earnestly in March of my M2 year (the exam was in June). I, like most other sources that will attempt to give you advice, will repeat the old adage: Do what works for you. Some prefer doing practice questions from QBank. I took a different approach.
Interestingly, I decided not to use any practice questions whatsoever. There were many reasons why I chose this (financial constraints, different learning style, etc.). Instead, I used the 1 or 2 best sources for each subject and made notes in my main guides. I used First Aid for the USMLE Step 1 as my main source of information, but because I knew it was not in-depth enough, I supplemented it with several other books. The following is a list of materials I used when preparing for the test (in rough order of importance from most to least):
Main Guides: First Aid for the USMLE Step 1, BRS Pathology, Goljan audio lectures
* Note: If I had to do it over again, I would NOT order the expensive Kaplan Organ System books. My experience with them was not particularly good, as I found them incredibly dry and FULL of errors.
** Note: I was a biochemistry major in undergrad, so I may have somewhat more enthusiasm for this subject than others. I chose to create a large poster-sized version of Nebeker's biochemistry map. This served as an all-encompassing resource of the various metabolic pathways. I also placed notes on key reactions and enzymes as well as clinical correlations directly on the poster (e.g. G6PD deficiency). This method, although quite time-consuming, really helped to solidify all of biochemistry into one framework. Only for the motivated, I suppose.
Keys to my strategy:
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Alpha Omega Alpha
http://www2.uic.edu/stud_orgs/hon/aoa/