1. Read the history of this forum to get plenty of discussions on Step 1/AOA.
2. Study VERY hard, because most of your class will also work hard - making it difficult to stand out. Study full time for 2 months for STEP 1. Make a 240 or better if you can. Dont cry if you dont, occasionally someone with a 230 gets in.
3. Between during first year, or between first and second year do research electives with someone known in the field at your school. If none is there who is known, do work with someone in another field who is fairly friendly, publishes alot, and lets students who work on papers put their names on them. Use PubMed to collect intel. Are they publishing this year? Has a previous student written a paper as first author? Thats a good sign. My chairman did research in cardiology during med school and went in to plastics. It only counts if you get published.
4. Make good grades.
5. Be nice and helpful to others at your medical school, even the people that dont seem to matter. A bad attitude is noticed, med school campuses are a small community.