The most important thing, when it comes to making the most of college, is realizing that the primary purpose of college is education; if you are a parent, encourage your college student to keep this in mind - and if you are a college student, realize that there are plenty of fun times to be had in college, but that these times will only continue to be fun if you continue to put your school work first.
Of course, some students fall on the other side of this - students who end up getting so wrapped up in college that they fail to enjoy any of the college experience; if you are this sort of student, realize that college only comes once in a lifetime, and in addition to getting great grades and setting yourself up for a successful future, you should also make the time to have fun and make lasting memories.
And when you are in college, you should always look for opportunities to accumulate valuable like experiences - not by getting in trouble, of course, but by finding internships that will help you learn about your future career, by working closely with your professors, by getting help from upperclassman whenever you have the chance, and by helping those underclassmen when you are in a position to do so.
As you go through college in this manner, you will be able to maximize both your education and your fun - which will allow you to maximize the investment you are making.