I was in a similar position to you at the beginning of college. Making conversation is really just about asking questions and following up on them. If the other person can't respond with their own questions they are either lost in thought (like y.t.-- sorry to everyone I've ever talked to) or just rude.

For people attending school:

What clubs are you in? What classes are you taking? What's your major?

For people in general:

So, what do you do? (this is old and cliched but still legit) Or if they are doing/wearing something distinctive ask them about it.

You might be tempted to ask something more specific to what drives you personally, but that's not the way you establish interest in someone. I sometimes jump to my favorite subjects after 10 minutes of chat though.