Folders, youโll get so much loose paper that you wonโt be able to keep up with just a notebook.
I have a lever arch for each subject at home, then a normal sized folder I take in every day divided for each subject, and I take lined paper in each day. I only transfer work to the lever arches when I finish a topic.
Optional but not at all necessary: when it got to revising for my exams I had three of those expanding files with pockets in, one file for each subject.
Then Iโd label the pockets with each topic for a subject and Iโd use them for revision resources Iโd made such as posters, flash cards mind maps etc (my college notes stayed in my lever arches to refer to)