PLEASE HELP - GCSE AQA Triple Science revision helpWatch
I would recommend as a starting point: look through your notes every day/week - make sure you understand everything that you've done in class (and if you're reviewing it regularly, you can spot any problems early and ask your teacher about it whilst it is still relevant!). Do this at the end of each topic too. The more you understand as you're doing it, the easier revision and exams will be. Also, read your textbook (it sounds daft, but sooo many students ignore the textbook if their teacher doesn't explicitly say to read it).
When you know what topics are easy/difficult for you, make sure you pay attention to the difficult ones. It's easy to fall into a trap of reading and re-reading the topics you like, and avoiding those you don't! Reading and summarising is a good technique. Highlighting often isn't, especially if you're one of those people who tends to highlight EVERYTHING without really taking in the information. Make posters or diagrams when it makes sense (e.g. for synapses, I made a little flip book during a supply teacher lesson). Learn your definitions - make a glossary or flashcards, or use an app that allows you to learn words (I can't think of a science one specifically, but something like memrise where you learn vocabulary).
Finish exercises too - if your teacher gets you to do questions from the textbook (or similar) - do them ALL...and check the answers. When it's closer to the exam, you can use these answers to revise, and even repeat the questions without looking at your work.
Doing questions and practice exams or past papers is the best way to set yourself up for doing well in the exam. Exam TECHNIQUE is important as well as the content, for example, you might have an answer sort-of-right, but get more points for writing it in the way that the markschemes want. So do a practice paper, get hold of the markscheme and mark (honestly) what you've done. If the first attempt is bad, don't be too worried, but use it instead as an opportunity to work out where you lost marks and why. This works for a lot of subjects too, not just sciences. I, for example, recently did a music theory exam paper, was a little disappointed with my score, but realised that I would have got 6 more points for avoiding silly mistakes, and another 2 points for describing something in the specified way. So pay close attention to what it is that you actually get marks for. In most sections, you can't get credit for being awesome and knowing stuff that isn't actually asked for in the markscheme.