I agree with mimib. The giant desk calender is great. The way I plan to set my up for the fall is, once I have my teachers picked, I'm going to print up their syllabus, and write in all the due dates on my calender. Also, I color code each class...and, I've hung the calender on the wall across from my bed, so that I see it first thing every morning, and know what I need to work on.
In addition to that, (I take a couple online classes) I make folders on my desktop for each class, so that notes and assignments have a home, rather being lost in documents. I also "name" each assignment by class code and assignment/chapter #. And, if you do take online classes, make sure you print up your notes/reviews so you can look at them away from the computer.
Good luck staying organized.