Is it better to cover information in detail and have say, 40 pages worth or is it better to only briefly mention things and have 20 pages? And how do you cut down if you have too many?
I personally try to be as brief as possible without completely removing context or phrasing things in a way that eventuates in me having no idea what I was learning. I still manage to end up with far too many though :(. How do you do yours?
Write your notes down in a way that is consistent with your learning style. I usually write down facts and figures with a brief explanation because those are the vital parts of education. But, if I don't understand something, then I'll write down more. Brief and concise notes are best for reviews and studying for tests. For actually understanding a certain concept, more reading and studying might be required. For those things, write down websites and resources and don't forget to go back to them until you fully understand the concepts.
I suggest taping lectures, if they are lectures, if it is allowed. You can also tape yourself talking your way through your thought process, or explaining things. When I was in college, I used to tape my professors and then listen to the tape in the car and at home. At home, I would listen to the lecture and follow along on my notes.
Every indiviual has his own style of learning and making notes. Tinicraw has made very good suggestions. When I was studying in college, Internet was not there but I used a similar method. For me it was the concepts first. After I have made these things clear, surely by revising what has been discussed in the class immediately after returning home from the college, I would flag the books with book marks. I did not use any study notes because one would always miss something. I surely used to solve problems in my subject note book that I felt may have some difficulty, not all problems in the exercise. These steps helped me to revise the subject before exams. But as I said earlier, every student has to find his own way to learn that suits him/her best.