@ohdearieme had excellent advice: a plan and rest breaks are definitely the things you want to do.
You might want to try some timed revision within this - such as the Pomodoro technique, in which you do 25 minutes one subject/topic, 5 minutes rest, repeat for 2 hours alternating between subjects then have a proper break - it's a nice method. It's definitely said not to waste time making notes - you should focus your revision on things you know and revision things you've made, such as flashcards. Blurting is also a popular revision technique: cover up your revision guide or notes and write down everything you can remember. Repeat another day and try and recall what you forgot: it's a nice way to embed ideas before an exam.
Before you actually start revising, draw up a list of the topics in your subjects you want to revise - or check out their Specifications on the exam board website. Then, pick around 5 of the topics (or less if you feel confident) that you feel the least confident with, and focus your revision with those so you're getting knowledge for that. Revision is not a one-size-fits-all approach, but it's worth trying multiple things to see what you find best.
Best of luck with your exams!