You can read something and hope that it’ll all be beamed into your brain for future application. Or you can read it and write down what you just learned, as if you were teaching someone else, and actually retain it. This is called the Feynman Technique.
In other words, implement a more “active” way of learning, which obviously takes a lot more work than it sounds. Ideally, when you write down your learnings, you’d also repeat what you wrote aloud, like a teacher instructing a class. With this method, you discover all the areas that need improvement and can go back to focus on those weak points. Repeat this until you can explain the topic or idea in full and simple details. “Once you can explain an idea in simple language, you have deeply understood it, and will remember it for a long time,” the video explains.
Source: The Feynman Technique Helps You Study Faster and Retain More Information
Tony Gurney 