combined science higher Watch
go through the topics and write exam stye questions, meaning of words, questions with lists etc on one side and the answers on the back. This will help you go through the topics and memorise information which will then make it easier to answer the exam questions, especially when you're doing science.
I wrote up all my notes into a nice notebook and then I made mind maps for each topic from that information. They were detailed but simple looking, along with revision cards to go with them.
Then I would complete exam questions on that specific topic and keep all the stuff for each topic in it's own plastic wallet in my folder.
I also was lucky enough to use MyGCSEScience as my friend had a subscription which she let me use.
Primrose Kitten on YouTube makes revision topics for every exam board for GCSE science including an hour long video where she goes through everything for each exam. I really recommend her. :-)