Hi there. I would say make sure you understand all of the course material as you are covering them in your lessons with your teachers and if something confuses you, ask teachers to explain it right away instead of leaving it till exam time. In terms of revising you could make posters, revision cards, rewrite your notes, make use of colour as it aids in you remembering things better, and also near exam time get a hold of every past paper from thw specification you are doing and work through them. Take your time in doing the paper and also rechecking it for mistakes. Mark your papers using the online markscheme and study them to see what type of question requires what kind of point to get the marks.
Hope this helps.