just did my GCSE's like a year ago but the way I studied was using websites like save my exams, PMT ect and just reading over the content. after you read over you should take a short break and then write or say what you just read. that way you can place that information into long term memory. however the night before my exams I would go over any past paper questions. BTW if your wondering what i got i got 7/8s in most exams. 6 lowest.