This method works for most subjects. I always did this for math and I'm currently doing this for science as well (I'm really bad at science).
So basically I go back to the syllabus which is being tested and then I create a 'revision sheet'. I would put sub-headings and notes for that (maybe some pictures as well).
I soon realized that I am also, in a way, revising while I making this revision sheet and when I'm flipping through it. Double revision! :) :)
Here are some examples:
What method do you use to study? :)