I'm a fourth year Harvard Medical School student, which doesn't really make me an expert in answering this question but I can at least tell you that myself and my classmates don't have perfect GPAs, MCATs or the like. And honestly I'm not too sure how much academic performance has in acceptance. Sure I think they are important but I think they don't really differentiate you, only help you clear a hurdle.
My tip: you need to be someone who is passionate about something (as to what that passion is, I don't think the admissions committee cares).
When I talk to my classmates, I see that they are smart but struggle and work just like every other medical student, but each of them, if you get them alone can talk your ear off about something they are deeply interested in. More than that, they can make that topic entertaining. That's what I find impressive and what I think the admissions committee probably is after.
Anyway, I would probably just caution focusing too much on the academic side if that overly detracts from you engaging and doing something that you find interesting and rewarding.
Rob Montgomery, upvoter extraordinaire