One very important thing is to WORK during your free periods =)
It's funny how in year 11, most people didn't do much during frees, but this year, every free, everyone is doing work.
For us, the school reccommends we do 3-4 hours a night, 5 nights a week. Any hours you miss out on, catch up on weekend. Of course, this varies from person to person, but anything less than 2 hours won't be enough if you want to do well.
As for cramming before exams, it's not a good idea =) It works to a certain degree, but places extra pressure on you to memorise a terms worth of work two or three nights right before the exam.
It's much more helpful if you revise topics as you go. If you do 3 hours work a night, spend 2 hours on homework and 1 hour on revising previous topics, or doing past papers. That way, you build up a solid foundation. Also, don't do it all at once. Do an hour after school, an hour before dinner, and another hour or two after dinner.
