If there is a particular passages that really stands out I will note it down. I have a little collection of those (and other quotes) I sometimes read through.

I also tried writing in the margins on a book. I don’t like writing in the book due to it losing a lot of ability to shared after the fact, or if the book isn’t mine it’s a non-starter. That said, it was a very different experience, it was more like having a conversation with the author.

I may need to experiment more to try and find something that works.

I recommend looking into the Zettelkasten method for note taking, if you are not already familiar. It is originally used with index cards, so you might find it to be a useful way to handle taking notes on index cards. I use a Zettelkasten-inspired digital note taking system called Org Roam. The thing I like the most about Zettelkasten is that it minimizes the effort for getting your ideas out of your head. You can worry about organizing the ideas after you have them laid out in front of you.

I’ve considered reading on the computer, maybe I should actually give it a try.

I should note that I haven't actually gotten into a workflow where I read ebooks and take notes. Most of the reading I do is documentation for systems I program with. I take tons of notes on documentation so I can easily find what I need again in the future.

I think having a whole sheet might help. It's not enough to copy everything, but enough not to get sidetracked. Also, you might write down a reference to a page and 1-2 keywords only, or a couple of keywords describing one's own thought regarding a piece of content + a page reference.

* They remove cleanly, if you're worried about permanently marking up or defacing a book.

* They are easy to write on (I've mostly used EF nib fountain pens).

* Best of all, since they are color-coded, you can invent your own scheme (e.g. blue == "I should revisit this", yellow == "my top N favorite quotes from this book", etc.)

Edit: to add another point

* They are large enough that you can write a decent sentence in there -- the "page flag" size might be a tad too small for that (but thanks to the EF nib, I often find myself using different-colored flags).

Before they started writing regularly they were just a Zambit and look at them now. And who knows, you could make beebman following their method.

I also believe I spend much more of my mental capacity on reason rather than recall. I think I have gotten slightly better at reasoning due to that, just going off how I feel when I try to reason about things; I feel more lucid than I used to. Trying to "remember" things is really more of a mechanical process for me than it is a mental one. I think of some keyword that is vaguely related to the concept I'm interested in, and then hop around the hyperlinks and backlinks in my notes until I find what I'm looking for.

Sometimes I will start this process to find a spot that I want to start writing a new note, only to discover that I have actually written the note already! That is always a trip when it happens.

Just the act of writing an idea or a concept down helps to instil it in your mind, helping you either remember it or continue conceptualise the material you are learning about.

Reading, learning, doing and writing it all down is a powerful combination to accelerate learning, at least in my experience.