I took an hour and a half nap, went to dinner, watched two hours of television, and then went to sleep. The next day after my last class ended at 6pm, I came back and looked at the assignment sheet. I freaked out when I discovered all the reading that I hadn't done, in addition to some calculus homework. Don't take too many breaks or at least take shorter breaks, and always get started on the next assignment. You'll realize when you do, that the material makes a lot more sense than if you hadn't.
Time management is very useful in college, too.
It's important to make many friends and maintain a social life. And when life gets hectic, stop for a second and take a walk. Look at the surroundings and close your eyes. Don't think about anything, just relax your mind. When you come back to do that homework, your mind will be fresh and that hard math problem will suddenly become easier.