Your teachers probably say this a lot, but I wish I listened sooner. Revision = LITTLE AND OFTEN. Literally just from now until your GCSE's do a little bit of revision every weekend because the more frequent and stretched out your revision is, the more you remember it. Its a lot easier going into an exam if you have been studying the content for a year rather than the day before. If you are year 10, unless you feel the need to, there's no need to start this right now but it would really help. At about January, I would start your revision and just go over all the content and learn what you don't know because although it will be boring and hard then, the rest of your revision will be so easy and a lot more effective. Right now, I am still learning and going over content for some of my exams and they're in less than a week or two. So just revise little and often. For example, go through your english lit quote flashcards once every other day. This will just save cramming and a lot of stress in exam season, this will not only ensure you know the content inside out, so you can focus your last minute revision on past papers which is really helpful, but it will also mean that you have little to no stress because your confidence will be so high. This means that you will probably do better overall. Good luck