It depends a lot on the topic. For coding/tech, I find working through an "organized collection" of video tutorials by rewriting the code locally and taking not

It depends a lot on the topic. For coding/tech, I find working through an "organized collection" of video tutorials by rewriting the code locally and taking notes along the way, works very well. It's time-consuming, but I tend to retain more concepts after watching, listening and practicing, since it engages more senses (vision, sound and touch). Prior to learning a new topic, I try to make mind/concept map of the material based on my initial understanding from reading articles or browsing books, docs and examples. It also helps to have an end goal or project in mind to connect concepts to actual outcomes. You can also try explaining what you just learned to a non-technical person; forcing you to "make sense" of a concept while converting to non-technical jargon. Overall, it just takes time. After years as an autodidact, I haven't found many short cuts around hard work. There are many great techniques out there--some will work for you and others won't--but consistent practice is usually the underlying theme.