For physics and chemistry I went through my notes/the course companion and hand-wrote all of my notes, condensing the entire course into about 30 pages. I then went and typed them up onto the computer, so that I'd go through them twice properly. Now I just review my notes, do practice papers and questions from the course companion book.
I don't really revise for English since it's the only subject I'm naturally good at, but I'd advise making sure you know the plot well, and perhaps memorising a few key quotes. You could impress the examiner by throwing in a significant (relevent) quote. Other than that, if you're struggling, then practice analysing poems/prose and practice essay writing. Do it in this form: point, evidence (e.g. a quote), explain (THE EFFECT IT HAS ON THE READER). And don't forget to mention literary devices. If you use that method, you cannot fail.
Maths... I don't know, lol. I'm flunking maths at the minute. Any tips are appreciated.
IT in a global society - pretty easy as long as you can write essays well. Just memorise keywords and make sure you know your case study well and you should be fine.
Good luck to everyone.