By far, the most important thing you can do in college is network. Join clubs, participate in sports, get to know your fellow classmates and professors and make sure they see you and your integrity. College is a different kind of challenge, but it is one I recommend to people that want some additional practice at "life" before they live life.
It also teaches you some strong life skills, such as "how to not die when your parents aren't in charge of you." You learn life skills such as keeping yourself hygenic and healthy. You learn how to be independent and responsible as well. These things should not be taken for granted.