There’s a ton of books and material on this, the one that I enjoyed is the class on coursera called “Learning How to Learn”

The 2 biggest lessons from the course is:

Spaced Repetition

Repeating a concept to myself reinforces it, the timing is more close up front, and then can be spaced further apart. This works better than “cramming”.

Diffuse vs Focused

Diffused thinking is using the subconscious, and connecting the dots. Focused learning and thinking is on building the dots.

Separately I really enjoyed the book Thinkertoys, it’s a “cookbook” on Creativity Training.

References:

Learning How to Learn: Powerful mental tools to help you master tough subjects

Thinkertoys: A Handbook of Creative-Thinking Techniques (2nd Edition)