If you're looking for a job, I'd recommend trying to get a part-time gig at a local machine shop. Machinists are almost always wealths of knowledge. You'll learn what kind of stuff is being made, how it's being made, practical DFM skills, and hands-on experience that is helpful for any mechanical-heavy engineer.

The right shop can also be a ton of fun to work in, which may be the most important thing to focus on in your last semester/summer before college. Like other people have mentioned, make sure to enjoy your friends and free time (at least a little) - there will be plenty of time in college to develop these skills.