To begin with, one course that came as a revelation to me is a music history class I am taking right now. In high school, classes were usually very general, broad, and standardized. But in college, there are hundreds of different courses you can take about random niche topics. I really discovered how true this was when I was registering for classes for the spring semester. I needed to take a gen ed class in addition to my major specific classes, and I wasn't sure what to take. After browsing through a fair number of options, I found a class on the history of popular music from the mid-1800s until present day, with a focus on the development of rock music. I have always loved music, and it was very cool to be able to take a class and get credit for something I'm so interested in. I would suggest that incoming students look through all the options for gen ed classes before picking one. There are so many cool classes out there to take, you just need to find them. I would also suggest taking a wide variety of classes, because it broadens the range of topics that you're learning about during the semester, which can make the workload easier to handle.
Over the spring semester, I became pretty close to my BIOE120 (Biology for Engineers) professor. He is an extremely compassionate person and a great connection to have within the department. I developed this relationship with him by going to office hours and several learning sessions throughout the semester. Additionally, I made sure to ask questions and talk to him during discussions. I would recommend incoming students to do the same thing. Having close relationships with faculty members can be extremely beneficial later on, especially regarding letters of recommendation and even getting set up with internships. The main obstacle is that many classes are huge, and it can be difficult to get to know the professors when they have so many other students to deal with. Going to office hours definitely helps, though, because there is a better chance of having longer, more private conversations.
My relationships with fellow students have helped me cope with the adjustment to university by providing me with a support system. I made sure to make friends with people in as many of my classes as possible, just so I can have people to lean on if I need help on a particular assignment. I highly suggest incoming freshmen make friends with other people in their classes - it is especially helpful if you're ever out for a day or two, because then you can get notes from them. It's also critical to find and join clubs you are passionate about. Friends you make within these clubs are important, because you can decompress with them by doing something unrelated to schoolwork, like playing a sport.
The aspect of university academic life I was least prepared for was the amount of material covered in a semester long class. In some of the more intense classes I've taken in my freshman year, the pace felt nearly twice as fast as in some of my classes in high school. Not all courses are like this, but on average they definitely move through topics quicker. As a result, it means you spend less time on each topic, so you learn it less well. Furthermore, when an exam comes, there's more material you're being tested on. The biggest struggle I found coming to college was that I needed to dedicate significantly more time to study for exams than I had ever done before. As long as you know in advance to do this, it's not too much of a problem. For freshmen, I would just suggest that you make sure to plan ahead of time, and leave large spaces in your schedule to study for exams. It's better to have extra time to study than not enough.