the best thing i found (i'm the world's biggest procrasticator) was to create a timetable of revision. so each subject had it's own slot in the day. i never made any slot more than 1.5 hrs long as my concentration never lasted that long! i also scheduled in plenty of rest breaks for snacks and drinks.
i also colour coded a lot of my revision notes with highlighers, e.g. pink meant really important point to remember, yellow meant background info.
always make sure that the room you are studying in as plenty of natural light, a comfortable chair and big desk so you can spread you work out. and make sure it's tidy - it's amazing how appealing housework was when i had maths to revise for!
good luck!