Ill try and summarise some of my tips, but remember that everyone studies differently and what may work for me may not work for someone else.
1) Organise your notes. Now I'm not just talking plastic wallets for each subject, or a drawer full of exam paper questions. Get a lever arch binder for each subject and keep your notes, exam paper questions seperated by topic e.g (cell biology/ organisation etc) Then when you come back to it nearer to exam season everything will be in one place and easy to acsess.
I have a video below which is an hour long but is summarised in the comments. If you can't purchase them yourself then charity shops and online may have them at a discounted price.
2)List your subjects in order of difficulty and how far away you are from a projected grade. This will help you focus on where to revise the most.
3) I can't emphasise enough how
quality>quanitity. You don't need to be spending so many hours every day revising. It's what you do that is important.
4)Keep a notebook and make a checklist of 5 simple things everyday of what you want to achieve.
If you feel like a study timetable isn't for you, and your stuggling to keep up with it, I reccomend using a retrospective timetable. Again if you are interested I'll link this below for you to take a look at. Trust me, it isn't as complicated as it looks.
https://aliabdaal.com/retrospectiverevisiontimetables/5)If you revise in 1 hour chunks for 6 hours then your less likely to retain the infomation, but working in smaller chunks, with breaks, may mean that you focus better and you don't lose motivation. This is the
podmoro technique. Get a timer, and study for 25 minutes, then pause for 5 minutes, then continue, especially if you may have ADHD or a shorter attention span. Also, if you feel like you haven't progressed, then it's probably because you aren't checking whether you can fully
understand and apply your knowlegde to exam paper questions. You can use physicsandmathstutor, or go to your specification's webiste for past papers.
4) Finally, progess takes time, and a habit takes 27 days to form, so once you get revision right, you will see the results. Trust me. I went from a 5 to a 9 in physics, so I believe you are fully capable of anything.
5) Don't rush revision, even if your exam is a week away. Just focus on the topics you struggle on the most. If you have any other questions I'm more than happy to answer them.