Do be sure to get a firm grasp on electronics. Build a linear power supply, get a breadboard and Arduino, and just play with things. Make sure you understand how it all works. Learn FPGAs, and other non-Von Neumann ways of computing, maybe even try out analog computing, if anyone has some things to try out. You want to understand what holds up the computing environment, and having that understanding, even if it's not super deep, can be very valuable later in life.

If you can, learn a bit of machining. You're going to be in a place where you can pick up a ton of skills unrelated to your major, with almost no effort. Plus those can be completely ungraded, and at your own pace, so there's no stress. (Again, quite valuable at unexpected times, and fun!)

As you make friends, take the effort to keep in touch with them, it doesn't have to be pushy, just don't succumb to the natural tendency to follow "out of sight, out of mind". (I've done that too much)