Hey I did biology and chemistry and I think what is most important is finding a study method that works for you. For both subjects alike, I made sure my notes were in order from the start. Used the textbook for biology notes and for chemistry I printed off online notes. Before mocks, I gave myself a months to fully revise. The first month I read my notes (first two weeks and tried to fully understand the concepts (don’t memorise)) and did all the past papers I could find. With this I noticed how some questions would come up again and again and so would write down full on mark scheme answers in my notes (did this especially for biology for bits on protein synthesis, dna replication, photosynthesis). A month before my actual exams, I reread my notes and was able to see which bits of my notes will be worth rereading (this time full of mark scheme answers). I also redid all past papers leaving the most recent ones to do 2 days before the exam. If you did Edexcel, I am confident in saying that understanding what you revised is key as the questions this year were there to test your application of knowledge. Even doing the IAL edexcel papers (units 1-6) I believe, although repetitive in their questions, helped solidify my knowledge in weaker topics. Hope you find this useful and I wish you the best of luck for your exams next year!