My advice is probably better suited for a liberal arts major (compared to a STEM major, say).

Learn more than you know now about the jobs that your field of study might support -- especially salary and life style. This seems like a big blind spot to a lot of students.

Go to professors' office hours. They are fascinating people and know way more than you do. (P.S. I'm not a professor.)

Audit classes that you wish you had time to take.

Actually do the homework before the class in which it is due. (This is less of a problem for STEM majors than in humanities and many liberal arts; in the latter, homework is often just reading.)

Do the optional reading, even if it really is optional.

Take extensive notes on the reading. In class, focus on listening. Good lecturers are synthesizing the facts you should already have consumed. Your notes from class should be much briefer. You should be able to study for tests strictly from your notes, without needing the book, except as an occasional reference.

Sit near the front of class.

If you have to choose between one semester of microeconomics and one semester of macroeconomics, take micro.

Take at least two statistics classes.

Leave your video games at your parents' house.

Learn an exercise routine that you can stick to for the rest of your life.