Out of your A Level choices, I only do history but I can give general study advice.
Like the above poster said, make flashcards as you go along (if that works for you) and make sure you regularly go over the content - this is especially important in history as it's vital that you can recall the facts and general timeline for both essays and source questions
Practice practice practice!!! (exam questions) - once you get further into the academic year this will help you get used to A Level style questions and you'll be very prepared for mocks. Hopefully your teachers will be happy to mark anything you need them to
Read around the subject - I'm not sure if this is useful for film studies and computer science (maybe do extra research instead) but for history reading extra books around each topic will be extremely helpful when considering different theories, themes, and ideas. It's also very impressive in exams if you use quotes from historians.