1) Don't let anyone tell you something is too difficult.
2) Don't let anyone tell you something is too difficult.
3) Double major in your favorite humanity (english, history, art history, religion, etc) and your favorite hard science (physics, chemistry, biology).
4) Summers are not for coursework, summers are for summer programs (NIH undergrad, Foreign language immersion programs, Tropical medicine in costa rica, interning in Washington D.C. etc.)
5) Work in the most famous lab on campus. People may tell you that name doesn't matter, they are wrong. Being around a lab for a few years will allow the PI to write you a solid letter.
6) Show leadership in something (greek social chair/president/etc doesn't count) service clubs are great, community organizations are also great, human rights organizations are great.
7) Clinical experience - free medical clinics are probably the best experience b/c they are usually small and you can hang out with physicians. This can usually be combined with good summer programs!
8) Don't be afraid to take a year or two or three off after college before applying to med school to do something you love. Peace corps will get you into a lot of great schools if your grades are competitive, but it's a huge commitment.
9) If you have the motivation and desire to be a doctor, you can disregard everything I've said except points 1 and 2 because you will find a way!