At the start of each subject, find out the exam board and full course name and print out the specification for each. Then when you've learnt something new, you can tick it off if you understand it, or put a question mark next to it if you need to go back and take a look later on. Obviously don't just ignore the parts you do understand, as you will still need to revise them later, but it gives you an idea of what you need to work on.
Also, teachers talk about revision timetables, but in order to make sure you do enough work outside of lessons throughout the year, plan a term timetable for outside of school, and stick to it. You're guided to do an hour outside if school for every hour you do in school, so if you can fit all of them from one day in that evening, then things will be fresh in your head and you will still have weekends free. You can then use this time to complete homework and coursework, making sure you won't end up cramming before the deadlines!