Basically this but for yourself: The Feynman Technique

Take a paper

Write a headline about a subject you're trying to learn

Write down how you'd explain it to an audience fitting to what you are learning, grandparents seem to come up often...

As soon as you can't explain a concept in simple terms - you've found a hole in your knowledge. Probably a good thing to fill that gap.

Then re-do the explaining. Find a knowledge gap and patch it. Repeat until you know the subject.