I work through books, go through a whole book and make notes on the things I need to know Then add from my own notes and colour code and stuff. I get really picky that my notes have to be superly neat lol then I just read them over. I make revision cards of things that have a question on one side and the answer on the other, then answer them all the time until I know the answers. I make a glossary, and then get someone to test me on it to make sure I understand the basics of everything. Then for the things I really struggle on I'll make a mind map, with diagrams because then I memorise the diagrams and take it from there It's a very loooong process for me haha. Then for formulas I am not so great, I just have to write them over and over, and I speak them out loud with someone testing me.