I can't put enough emphasis on the old stalwart of keeping your notes organised right from the start of the year. I took four AS levels and GCSE Latin last year and I have to say that I didn't always follow these rule, but I wish I had. It just makes your exams so much less stressful if you know where all your notes and revision materials are and you don't waste your precious revision time tearing through your folder.
P.S. Another sneaky add-on to this advice, I would recommend that you have a separate ring-binder for each subject that you use on a day-to-day basis, with a lever arch file (with file dividers, they are life savers) for each subject's notes that you keep at home, transferring your old notes over as you cease to need them in lessons, so you don't have to drag all your notes around with you everyday. It's saved me from many, many pulled muscles in my back and shoulders from lugging around an unnecessarily heavy bag.