To learn something new, you can divide it into chunks. Those mini chunks can then be learned individually and once mastered your brain can fuse those small chunks into one larger more complex one - like building a lego world by starting with one room.
To form effective chunk follow these steps:
Before you start, figure out the main framework of what you want to learn. For example when you study the war between Japan and America, make yourself familiar with the basics of World War II. One way to do that is skipping through a school book looking just at headlines and images before you start with a specific chapter. Another is to watch a movie about the war. A basic understanding of the subjects later acts like a superglue to attach the chunks in your brain.
Once you are familiar with the overview, it's time to focus on specific concept. Now you should not be doing anything besides learning that chunk. For your most focused learning mode you need your full capacity of your working memory and therefore you need to focus and avoid procrastination (the Pomodoro Technique might help). After you are done, test if you have learned the chunk.
The probably most effective way to test your learning is recall. In order to do that, try to repeat the material just thereafter you have studied it. You can do that by summarising the information in your own words, explaining the material to a friend, speak it out loud as if you were teaching it or by applying the concept in a different environment and creating graphic analogies. Only go on to the next chunk if you can successfully recall the current one.
Once you have mastered the small chunk of the subject, repeat the study of the underlying context, the big picture. Now all the mini-chunks will cluster together and create a strong network of interconnected synapses that will allow better recall, a deeper understanding and increase your potential for creativity.
Tips and Notes:
Use Spaced Repetition or what I call "sleep and repeat" to improve your learning outcomes. The technique advocates to deliberately break up the study of a certain concept into short chunks by setting a clear start- and quitting time. Once done with a daily dose of study, you stop and repeat the next day. During the sleep your synopsis will form new connections that increase recall of the learned material.
It is important to note that the process of working out the solution for a problem, is what creates the learning. So if you just look at a solution and go “oh sure, I would have figured that out” then you don’t learn it, thats just a common illusion of competence in learning.