Preparing for USMLE Step 1 is daunting. You know it is the one of the most important test you will ever take, and it will determine what type of residency you will be able to get in to. All that is true, but do not worry too much – with the correct preparation you can do well on Step 1.
As I mentioned before, the most important part of preparing for Step 1 is learning as much as possible and doing well in the first 2 years of medical school. You should give yourself about 4-6 weeks of intense preparation. Any shorter will probably not be enough, and too much longer will make you burn out. Set up a reasonable study schedule before you start and try to stick to it. Here is an example of a good study schedule that I used when preparing for Step 1.