If I want to actually learn what I'm reading ... I basically follow Louis Frenzel's advice from his column[0] in Electronic Design years ago (HN post[1]):

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All learning is self-learning. Professors, trainers, and all teachers just organize and present the material to be learned. They don't teach it to you. You learn it. You're the one who actually absorbs, understands, and assimilates the knowledge by listening to the lectures, reading, thinking, solving problems, and other activities. Self-learning is a natural, human quality. While most of you have used this method in the past, you may want to do it on a more formal basis to speed up and fine-tune your methods. Here's a suggested approach (and trust me on this, you must write it down):

- Clearly identify what you want to learn. Write it out.

- Write some learning objectives for yourself. These statements clearly identify what you want to know and be able to do. For example, you should write something like "When I complete this learning assignment, I will be able to design and program an FIR DSP filter." The objectives should be expressed in "behavioral" terms, that is, using words that state some measurable outcome.

- Identify some initial resources. Start with books at the local bookstore or go to www.Amazon.com or Barnes & Noble at www.barnesandnoble.com. Most cities don't have good technical bookstores, and it's tough to find anything at regular bookstores. Consider yourself lucky if you have a good technical bookstore or a good college bookstore. Plan to get multiple books to give you greater breadth of coverage with multiple explanations, examples, and perspectives. Don't forget to look through your stack of magazine back issues.

- Check out online sources. Do one or more Web searches, or go to relevant company Web sites. You may run across an appropriate tutorial, white paper, or application note that will give you what you need. The large semiconductor and equipment manufacturers have tons of stuff on their Web sites, so start digging. Also check out the professional societies and other sources listed in the tables and sidebars.

- Watch out for any conferences or seminars on this topic. Usually, such events never occur when you need them, but you might get lucky. If you find one, attend because it will provide a big head start for your own learning.

- Organize your materials. Lay them out, mark them up, and then make an outline based on your objectives. See what you have and what you lack, and make an initial list of things to do.

- Dig in. Set aside an hour a day or whatever you can to go through the materials. Turn off the radio, CD player, and television. Make a habit of finding some quiet time to read and learn.

- Look for a human tutor. You could be working just down the hall from an expert on the very subject you're trying to learn. Pick his or her brain. Ask this person if he/she will help you understand and learn. Take this person to lunch or offer to pay for lessons. Most people will gladly share what they know, if you aren't too proud to ask. The best way to do this is to learn as much as you can on your own. Then, go for the professional, personal help with tough questions or when you get stuck.

- Include some hands-on. Is there any hardware you can buy or put together to help you learn it? Maybe there's some software that will help. Buy it or have your employer buy it.

- Write a paper or article or teach what you have learned. You have to know it to write it or teach it. There's no better way to learn for yourself than to have to explain it to others.

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[0] https://www.electronicdesign.com/technologies/dsps/article/2...

[1] https://news.ycombinator.com/item?id=30332471