I was always pretty unorganised. My system, which I perfected just about the time I graduated, was a thick pad of narrow rule paper, and six ring binders (one for each course that semester). Take notes in the pad all day, then when you get home rip out the pages and file them in the correct binder. After your exams, store the notes in some cheaper place (e.g. using cable ties) and re-label your binders to your new courses.
Then buy about seven thousand bic pens, black blue and red, and store them everywhere (you WILL run out and people WILL ask to borrow it all).
Invest in a hole punch to store lecture handouts in the file too.
And NEVER lend anyone notes for more than the 5 minutes it takes to make a photocopy. They WILL lose them.
Pad, pen & calculator is all you'll ever need. But some good organisation pays dividends.