I'm in the same boat.
Set a schedule for yourself and stick with it -- don't make it crazy-difficult to keep up with, but
let it cover all of your topics in a manageable format. Say, two hours of revision per night - an
hour on two different topics. Set goals (one exam paper every other evening, 3 hrs of maths per week, etc).
Give yourself breaks and reward yourself. Try not to over-work - all standard protocol.
Decide how you revise best and then try all sorts of other revision techniques to experiment which
you think will work best:
mnemonic techniques, group revision, test papers, note-taking, by rote... whatever!
Also target your weaknesses - if you're great at the maths non-calc, you're wasting the time you could
be spending on the calculator paper. Likewise for any other subject - you're not actually improving by
going over the stuff you know best. It may feel good, but go through the hell of studying your least favourite
topics, and you'll go beyond what is expected of you.
That's all I can think of for now! I should take my own advice. Good luck!
J