It depends on what works for you. I'm sure you've established which form of organisation works for you. I personally find loose leaf paper + plastic sleeves with a post-it note on the sleeve helps me to organise my stuff quite easily. Books are quite nice as well, as you can just flick through anytime but if you somehow lose it it's a problem and looking at it before exams can be an arduous process. Laptops have a very good filing system and you can store stuff online to access anywhere, as opposed to a book.
My organisation varies for each subject. For sciences, I would recommend using a loose leaf paper + sleeves to organise (binder). For math, I would definitely use a book and maybe loose leaf paper with formulas, self made examples. For subjects which require more writing, I would use a laptop so I can sequences my ideas more efficiently and add more content.
If you have any other questions, don't hesitate to ask.