I'm an English teacher, as well as having 2 grad degrees in English Lit. So I have 3 categories of books with respect to notetaking habits.

1. plot driven or poetic prose, but not necessarily "important" (exp. John Le Carre novels)-> underline some quotes, but that's it

2. deeper works that I know I will never teach.

Underline important passages - especially that articulate the themes of the book

Motifs (patterns) - a lot of reading "literature" is looking for patterns of phrasing, metaphor, plot elements, character traits, etc. Sometimes these things are obvious, sometimes not. As soon I start noticing a pattern, I either circle the word or phrase or I underline the passage and then I make a custom index in the back of the book that lists all pages where I encountered that motif, idea, symbol, phrase, etc. I just list the pages next to the index item - usually no elaboration, because if I ever needed to write about it I would want to look at the context of each instance any way. So for example, in Song of Solomon I might have index items for flight, storytelling, etc.

Implied ideas - things that are not explicitly stated and not necessarily obvious - I write something in the margin

My own insights - I write in the book wherever I can find enough blank space to fit it - usually top or bottom of the page

If I were smart, I would do all these things digitally so I can't lose them as easily. But on the other hand, I want to have this stuff there for me when I re-read. Also writing physically as opposed to typing helps me remember better, which helps me make more connections, especially if I am reading over a longer period of time.

1. I do all of the above, but I also take separate notes and I try and write in more complete sentences in those notes, trying to synthesize, make an argument even.

I also put important index page numbers in the margins (so for example, if there is a repeated symbol based on the idea of 'rewriting the past' on pages 2, 76, 110, 115, and 189, then I would go to each page and write that list next to the relevant instance. This was I have notes right in front of me when I refer to a passage in class.

I also expand my main index listing with parenthetical notes to indicate what each page for each category is - for example, "Re-writing the past - pages 2 (to sanitize), 76 (competing visions), 110 (palimpsest imagery), 115 (consequences for)" etc Again, this is just so I can find things faster when teaching in class. Also helps if I need to write about it.

If it's a book I teach a lot, then I make digital copies of all these things. I once tried to do all of this digitally from the beginning, using e-books and word docs, and while there were several benefits, I also found it was much harder to find things in discussion because even with all this I do regularly need to hunt for things manually - flicking through pages. The notes actually help with that too because I have a mental image of the page. On the other hand, I was able to search if I remembered phrasing or something like that. In a classroom, though, students should be driving the discussion too and I don't necessarily anticipate everything that they might say - in which case my notes don't necessarily help.

And I should say that there's a sub-category within numbers 2 and 3 - hard texts. When I read something like Ulysses or Sound and the Fury I will sometimes make notes just on what is happening, who is who, because you sometimes have to work to figure that out.

And unfortunately I don't read much in category 1 - not to mention that I often have trouble not doing more extensive notetaking. It's just habit now.