Top Down, Get the idea of what you’re going to encounter at each level before trying to “read the book”.
My approach to a book like that (educational) in a context like that (master skills to apply to my responsibilities):
Figure out what the author intends to communicate with me.(Start asking is what i want to know in this book? and Do I want to know what’s in this book?)
-Read the table of contents, top level, repeat reading any subheading detail, re-read a few times. Did I get an idea of what information is in this book?
[this is where I proceed only to specific chapters/sections if I have specific questions]
-I find prefaces and forwards a mixed bag. Once in a while I will get something added to my perspective of the subject that will enrich my understanding of the rest of the book. Sometimes it seems charming extract from the author’s diary and…zzzz.
-Read provided summaries at start and end of each chapter, Read the first paragraph, and the last paragraph of the chapter. Re-read in the last few chapters if your attention was waning by then as much as mine usually is. Is the end of the book a finale that pulls together the rest of the book, or are the last chapters things that didn’t fit somewhere else?
-Now read the detail, and get what you can or what you need out of it. If you ask me the top-level activity above starts to make space in the brain for the information to come and when I get into the nuts-and-bolts I understand it better and remember it better
-What do I know now that I didn’t know before I read this? Sometimes the honest answer is that I have only a vague impression of what’s in there. I may need to just repeat reading that part until I ‘get it’, but sometimes the most useful thing to do is look at other resources that cover the same topic and learn the topic from several angles.
I get how daunting a book or course can be. But be comfortable with not knowing yet and at first being bad at it – or if there is a history of difficulty in the subject area. Make space in the mind with zen emptiness. Chip away at that not-knowing with discovering what’s in the book one bit at a time. Be prepared to enjoy some of it, especially if something needed is learned, let that happen. Be prepared to redefine yourself from “I’m not so good with …” to “I was not so good with … and I do this now and it’s good”