Sat those three A levels this year! For maths:
1. make a poster/cards on content/formulae that you’re expected to know.
2. Make sure you understand content taught every lesson and try to answer some qs after every lesson to consolidate
3. Review chapters weekly e.g. do 5 qs on chapter 1 5 for chapter 2 etc. just for ‘recall’ and practice
4. Past papers!! (Ik everyone says this) make sure u do these under timed conditions once u have reviewed all chapters and if necessary do them again and again so u can master them
Bio: summarise!!! Print off your spec and keep this at the front of your folder and use it as a checklist for revision.
If u want to make flash cards make sure the content is consice and has what the spec requires u to know ONLYY
Same rule applies to posters/mindmaps etc.
Do lots of practice qs for each topic once u have reviewed it and learnt ur cards then move onto past papers!
(Make sure u learn the maths skills too for marks)
Chem: same as bio
Understand content, make revision material using spec and then topic qs then past papers.
Hope it helps and dont feel obliged to do all of these things, they’re merely just based on experience.