I learned this in college: use shortcuts in gathering notes during class. If I knew my instructor would say key phrases or words, I would use abbreviations accordingly, but be sure I knew what they meant by making a code system in the margin or on top of the note paper. I also used symbols to replace words: an = sign meant "as a result" or some other form of cause-and-effect idea. An upward arrow showed an increase or gain, a downward arrow showed the opposite. I gained time in keeping up with notes this way.
After class (this is CRUCIAL): I typed up my notes.
This gave me several advantages: I had the material reviewed once again in my memory, so I could "re-learn" it again. It gave me a study guide just before an exam that was legible, easy to follow, and also helpful for group learning. It gave me something to review when I needed it: no more sloppy handwriting to try and understand. It took time, but it raised my GPA from a 2.5 to a 3.75.