You didn't say what your major is, maybe you haven't picked one yet. In any case the correct way to choose a major is to first figure out what you want to do as your job after college, then choose the major that earns the degree that can get you that job. If you don't do this you may be stuck with a degree that only qualifies you to do jobs you're not interested in. Yes its true that many (most) people don't do work related to their degree, but that's less than ideal and you're at the point where you can do something about it.
Second, get an internship or co-op related to the job role you want so you can find out if that job is all its cracked up to be. Better to find out the job actually sucks while you still have time to change majors.
Go to class. If you're not a morning person, figure out how to schedule afternoon classes, or as late as possible. Use web sites like
www.ratemyprofessors.com to choose the best professors possible... this is very important and I almost always was able to get in the best sections for my classes by knowing which instructors to avoid and which to sign up for. It does make a big difference.
Books are expensive. Don't pay full price for new books, buy them used instead. Don't buy them until after you have your syllabus. Some times some administrator decides a book is needed, but then the instructor will say not to buy it. When you do know you have to have the book, don't go to the overpriced local bookstores. Google the ISBN number. If you don't know the ISBN, find out from someone else or go to the bookstore and write down the number without buying the book. Find the lowest price online and buy it there instead. Keep track of shipping times, get expedited shipping if needed as long as it makes sense price-wise. I often made a profit on my books by finding them online, used, cheap, and then after the semester was over selling them back to the local bookstores. I also sold them on Amazon when the local bookstores weren't buying them back for enough. Also keep your receipts for your books, its a tax deduction.
Again go to class. The first time I was in college, I went for Aeronautical Engineering, and I ended up failing a bunch of classes because I was more interested in playing X-Com World Defense till 5am then sleeping 6 hours, than going to any class that started before 1:30pm. I was an idiot and it cost me. In my defense X-Com World Defense was one of the best games ever made. If you're like me, cancel your World of Warcraft subscription and make sure you don't over-do your single player games, if that's what it takes.
Join a club. The second time I went to college (and I just graduated on the 3rd of this month, so while being in my late 30s, I have fresh memories of what its like) I joined Alpha Phi Omega, a co-ed service "fraternity", and I enjoyed it a lot. Calling it a frat isn't very accurate because its co-ed, and because its a service organization, not a social organization like the stereotypical party frat. I recommend them, but if giving back isn't your thing, join some kind of club. I also did the Humans Vs. Zombies club and the first time I was in college, the Paintball Club. These clubs are the kind of fun you want to have at college. And while they'll take up some of your time, they won't cause you to fail all your classes, in fact you'll probably do better.
And that reminds me. What you learned in high school about never starting a sentence with the word "and"... its roadkill. You can do it again now.
