How long do you have till your exams?
Heres how I do it (or rather, how I've done it this year for IB);
-Write out all your subjects, and prioritise what needs revising first - you can leave some till later (depending on gap between your exams)
-Break down each of your subjects - dont try and revise it all at once! for example, sciences will be broken down into topics, do a topic at a time, focus on the one you know you have trouble with.
-note wise, there are lots of things; get revision books (such as the science ones, or enlgish ones), make flash cards (by hand, or using software), make voice recordings (was great for languages I found!) GCSE websites - eg bitesize. funs games, and learning!
most importantly - PAST PAPERS! boring, but very vital! they'll show you what you do and dont know, and get you use to the lay out and time management
good luck