Writing out revision cards, or just shortening my notes and re-writing them. I barely use the cards, but writing it down seems to get it in my head more. I have a terrible memory, and the only thing that seems to work is writing it down. I always get up really early to revise on the morning of the exam too, because I find that last-minute cramming really does work for me.
During the exam, if I'm given an essay, I'll brainstorm everything I can remember on the subject for the essay, and then cross them out as I address them in my text.
I've also found that doing past papers (& then through marking schemes) has been immensely useful for the exams I've just done, because it shows you exactly what they want from your answer, so you get a feel for the kind of style they want.