You need to find and understand the behavior of your target audience ie. college students during the summer months.

I'd start with the most concrete thing, summer internships and take it from there.

Your goal before the summer should be to completely understand the audience. Where do they go? what do they do? what do they pay attention to?

Once you've done the leg work and analyzed their behavior start formulating some plans as to how to reach them.

You should brainstorm several ideas and keying in on the ones you believe will be most effective. I'd select 2-3 you believe will be your best performing and execute.

Be sure to track the data and determine which method has been most successful for you.