Start by seeing if your school has a mentoring program or something so that you can get in to shadow doctors. This is a great experience for several reasons: First, it will give you a realistic view of what it is like to be a physician and help solidify your decision to pursue this insane career. Or it might totally turn you off, thus saving you a quarter of a million dollars of debt and what would seem like an eternity of hell. Second, I forgot. Third, it gives you the opportunity to meet some physicians who could potentially write you a letter of recommendation. It does help to have a doctor say that you will become a future asset to the medical community.
Do not screw up your grades. Do well in your classes, even if you have to take a lighter course load. Try your best to nail your basic courses; physics, o-chem, biology, etc.
Try to make some time for activities that you actually enjoy. Try volunteering for an organization you really like; it doesn't have to be medically related. Working at a soup kitchen or something would be great. Don't pick something you hate just because it "looks good" on the application because you will be asked about these experiences at interviews and if you are lukewarm about them it will show and the adcom members will know that you did them so that they would look good on your application.
Start getting to know your professors; I did not do this and that wasn't a great thing. Go see them during your office hours. Explain to them why you want to go into medicine, what your interests are, and that you would like them to write you a letter of recommendation. Talk to them about your passions, your dreams, your interests, so that when they do write you a letter it's not just, "John was in the top 10% of the class, he got an A, blah, blah blah" because this is information that tells nothing about YOU.
