I improved my grades in the later undergrad years by taking the notes from class and re-writing them in a nice form (like you using colour and cleaning it up) into bound notebooks, like the kind used for log books. Then, if I needed to review for a test, I just grabbed the book. Now, I have a handy set of books on my shelf.
I'll add that the constraints forced me to focus on what was new and counter-intuitive to me. Limited space meant I'll have to trim away what felt obvious, and only keep the obscure.
The only problem with trimming away something you feel is obvious is that if you need to go back to the notes quite some time afterwards, it might not appear obvious at that time. It's just like when you don't comment something in code and when you go back to it, you're wondering what you were thinking when you wrote it.
