There’s a class on Coursera by Dr Barbara Oakley https://www.coursera.org/learn/learning-how-to-learn?
It gives you a basic model for skill retention. You should modify the style to what works for you. I’ve successfully retained what I’ve revised and practiced
Paradoxically, you're telling to learn a course that tells you right way to learn something.
So until then you don't know the right way to learn to learn the course you suggested.
