Congratulations, you made it to university. This means you're either smart, or very good with people. As I see it, there are two ways to make it here--either you get the grades or you get your teachers to bump them up for you. Both ways work, and both have their advantages.
University is your chance for greatness--this is where you reach your true potential. Whether you're the star student or the savvy slacker, you have a lot to learn.
If you don't like studying, learn to love it. It's tough to fly through university, especially when you take first-year weeder courses designed to kill you. On the other hand, if you sleep with your books, learn to sleep with people instead. Academia is great and all, but school is just as much about calculus as it is about new experiences.
You'll learn here that people are not created equal. If you are charming enough to impress your professor, you have a leg up on book-smart losers. But if you have no substance, you get exposed as a pathetic fraud the second you hand in an assignment.
Charm alone will get you nowhere. Getting an extension is nice, but there's still a paper to write.
The key is balance--realizing what your individual weaknesses are and working on them. If you're shy, join a club. Better yet, go out on Thursdays and get to know the good people at the Den. There are so many opportunities to meet people on campus that no one should ever feel lonely.
This is not high school and you will not be judged unless you're really strange. The sooner you lose your quiet shell the better.
At the other extreme, if you're at the Den five nights a week, you might become my friend but you will not pass your exams. Limit your fun to the weekend and hit the books between Monday and Wednesday (the academic week). School should be fun, but a Psychology degree with a 1.96 grade point average will not open doors after graduation.
Find your balance and stick with it. Life requires well-rounded individuals and chances are you are not well-rounded after high school. To be perfectly clear, you'll still be messed up after graduating here but the trick is to get closer to your personal ideal. For that, you have the three-to-eight years you spend at university. In both cases, that's plenty of time.
You are supposed to grow up here and you will. Beliefs and inhibitions will fade away, and many friendships will lose their steam away from the high school environment.
However, it is all up to you. The fun you have, your grades, who you spend your time with--everything is under your control.
By getting here, you proved you have all the potential you'll ever need. Now it's time to step up and make it count.