I'm finding that having little notepads for each of your subjects helps. The main exercise books consisting of approximately 96 pages, I leave for questions, actual essays, work, ie. These little notepads having about 300 pages in them, so I summarize literally all the main areas of each unit of the text book.
So for example, I'm studying Biology 3&4, so the Heinemann book will go in 1.1, 1.2, 1.3 intervals ie, so I summarize my notepad with the book so it's all compiled into little notes & I can remember instantly without having to search the main text book ie. With that, they're little & can fit into pockets & aren't that heavy. Also, do glossaries of any word you don't know. Keeping them in alphabetically helps with finding them later on too.
-Ephemera, Cranbourne Secondary.