I transform every chapter to some piece of code, either one already in it or of my own. If the chapter is only explaining the fundamentals of something, i make separate yellow notes in my study for a quick concept look.

If I don't understand something at all, i usually search for code samples in Github someone might have used or look for questions related to it on stack overflow. This gives me a general idea if what i am learning is complicated stuff, or considered difficult or unused or is complete bullshit.

At the end, I implement something by taking pieces from all chapters, & keep that project for later reference.

Also, when I am learning about something which is more of a framework, I try to find reasons of why something is done like that, look into internal implementations without getting into much complexity so that if ever this framework support goes off, I know how to implement my own smaller version atleast

I am a slow reader and I don't like any disturbances so I pick the best time to learn something, probably night time.