Such a good question! Yes, there are a few things I can think of that I wish I had done in college to set myself up for success early on - all related to making connections and learning more about the real world applications of the engineering discipline I chose. When I started looking for jobs, I had very few connections and pretty much no idea what my typical day at work would look like. I knew I would be designing water/wastewater treatment facilities, but I didn't really know what role I would be playing in those projects.
It's impossible to stress how important it is to have connections when you're trying to get an internship or a job. Having the right connection could be the difference between you getting a job you really want and you having to take the first offer you get for a job you don't want. Definitely try to make personal connections with recruiters and engineers as early as possible. One good way to do this is by going to career fairs. Don't make the mistake of just handing your resume to the recruiter and walking away. I know from recruiting for my company at career fairs that I don't even look at the resumes of people who do this. Take the time to ask questions, try to make a personal connection, and send a follow-up e-mail. If you make a good impression on people at career fairs, your resume might get some special attention when that company is looking to hire for a position you're qualified for.
I think the major way to make connections while you're in college is to be active in engineering-related clubs. My campus had a great chapter of Engineers Without Borders. The members of the club got to do some actual engineering design work under the supervision of several professional engineer mentors. Join as many clubs as you can handle, and go to events hosted by the clubs you don't have time to join. Hopefully your campus has a lot of clubs that will host networking events, educational seminars, and field trips. Even if you don't think you're interested in wastewater engineering (for example), and the wastewater engineering club on campus is hosting an event, definitely go! How do you know you're not interested if you don't really know what it's about? It's also important to keep in mind that the degree of overlap of the engineering disciplines in the real world is amazing. This is something I didn't realize until I started working. Wastewater engineers need electrical engineers, structural engineers, geotechnical engineers, even architects (to name a few)! So if you're an electrical engineering student (again just an example), definitely go to that wastewater club's networking event. You can talk to the wastewater engineers about the coordination between your disciplines and maybe meet some people you make a good connection that could land you a job in the future.
You can also become a student member of professional organizations in the field you're interested in and attend networking events, educational seminars, etc. hosted by those organizations. Another thing you can do is pick some fields you're interested in and contact a company that does work in that field to see if you could shadow one of the engineers for a day. That way you can see what their typical day is like and ask all the questions you want to figure out if that's something you can see yourself doing. And it's also good for expanding your network! I think it's also important to understand that just because you're studying one engineering discipline, you're not locked into a career in that discipline or even in engineering. I know a lot of people who studied engineering and are now working in finance or management consulting. I also know one person who studied aeromechanical engineering and now works as a wastewater engineer.
So to sum it up: clubs, networking events, expanding your knowledge about other engineering disciplines, and getting some (however limited) hands-on experience in the field(s) you're interested in.