I had a good MCAT score. My GPA was low for a medical school applications, but since I decided to apply to medical school in my Junior year, it simply reflected my pursuits up to that point. I never took less than 18 credits a semester and just as an example, my second semester freshman year I was taking Math 233, Chem 112, Physics 198, Physics 314, Physics 217, Physics 317, Biology 292 plus my required writing seminar. Not many pre-meds take 4 physics classes while taking the normal pre-med pre-reqs. I was taking Calc III and Chem II as they were required for my major and the biology was because I knew I needed to get stronger in bio for lab reasons. Starting my freshman Summer, I also started working in various labs. During the school year I was working 20-40 hrs/week, Summer closer to 70-80 hrs/week. I had a couple of publications, but those were miniscule compared to my lab contributions designing and building a beowulf cluster, writing programs to optimize genome analysis and annotation (I stopped by my undergrad a couple weeks ago while on vacation and noticed that at least 2 labs are still using the software I wrote based on their posters and the unmistakable drawings that my programs produced). I also TA'ed pre-med/intro Physics from Sophomore year until graduation.
So, MCAT, reasonable explanation for GPA, research, and teaching. Outside of that, while I haven't historically been the 'best' athlete in any group of people, you would have a hard time finding a sport or game that I'm not reasonably good at. I certainly have an ego that can get in the way of things, but I can very honestly tell people that project, sports, games etc. you will want me on your team. I am a superior communicator and I produce no matter what situation I am in. Oh, and I only need to sleep 4 hours a day. That is always a plus 😉.