The most important thing (like buying shoes) is to get the size about right. There are lots of on-line sizing calculators that will be adequate to put you in the right ballpark. That's good enough. Aside from that, I'd make sure that everything works and I suspect that you'll be OK. If you're planning to ride the bike on campus I think that you should either hold out some money for a GOOD lock or just buy a POS bike that you won't mind so much when it gets stolen.