> You need to make them your own. I second this, I found that I truly understand the material when I am in the position to explain it, to ensure that, I write

> You need to make them your own. I second this, I found that I truly understand the material when I am in the position to explain it, to ensure that, I write my notes as if I am an instructor and I explain things to a class under the assumption that they won't attend the lectures. As I write notes, I find myself needing to further explain things - so as to fit the requirements - which results in consuming more material and reasoning about it. This requires a non trivial amount of effort, and not everyone has the capacity to do it, but for a student, this probably works, the Feynman method and all that.