The Feynman technique. For anything you're learning about, try to write it down in a way a 5 year old could understand. Say it aloud to see if it makes sense. Simplify the concept to the most basic story.
The trunk technique. This is about learning the fundamentals (ie: building a trunk) for a subject first. For example, if you're interested in health, rather than learning about cold showers / eating 5 a day etc you'd learn about the human body and how it works. You're looking for the information that is going to stay stable for the longest and provide a base to build knowledge on.