Read The Intelligent Investor by Benjamin Graham and see for yourself what type of investor you are. In all honesty, you're young, like me, and have room for risk, more room than you will once you're in a lot of debt for med school and what not. In my view point, now is the time. There's something called Penny Stocks (Small Cap Stocks), though frowned upon by many (because they don't know how to properly value a company). These small cap stocks, usually not in the NYSE but in Nasdaq and OTC (over the counter market) can really make you money if you know what you're doing. And don't go asking stockbrokers or "qualified" people, you can do it all by yourself like I did.
While paying off loans is a really smart and good thing to do, you can make money on those loans. This is what I did.
First, there is a company called Canadian Solar Inc. (CSIQ - ticker), just remember this.
With student loans and private loans, I took out extra, I used that money to invest, didn't have to put a cent of my money for it.
Of course, I made sure I was picking the right time and all that, therefore I read tons of books and articles on valuation of companies and financial statements. YOU DO NOT NEED A DEGREE to tell you how to invest or teach you.
I did my due diligence, which was researching this company I found, CSIQ. Found it November of 2012, was at it's all time low (best time to buy, people will tell you not to but they're stupid, it's cheap, so buy). It was at like 2, i research for a few months and finally bought at 3 dollars a share. I put in all my loans, biggest risk of my life, but guess what, a year later, it went from 3$ a share to now +/- 40$ a share.
Moral of story, other than the fact that yes, pre-meds, pre-dents, students, adolescents (i am 19), do you know about this, it's called Financial Literacy and if you learn it, it'll do you wonders in life.
Back to Moral of story, haha. Take risk now, you're young, you can recover, if you want to make real money, you gotta take real risk, don't put it in an index that averages 3% a year, wtf is that? Oh yea that's playing it "safe".