The rash of "no way" responses makes me wonder: what note taking system(s) have you encountered that actually work for you? (And why, if known.) From someone who episodically takes notes in haphazard fashion and very rarely looks at them again, and thinks he's probably woefully working harder than he should as a result.
______
Step One: Choose the Concept You Want to Understand.
Write it on the top of a sheet of paper.
Step Two: Pretend You Are Teaching the Concept to a Child.
Write an explanation of the concept on the paper as though you were teaching a child.
Step Three: Stuck? Go Back to the Source Material.
Re-read or re-learn the material until you can complete step two.
Step Four: Simplify & Create Analogies.
If your explanation is wordy or confusing, simplify the language. Create an analogy to help understand the concept.
_____