There's no 'correct' way to revise, and if everyone elses teachers are anything like mine were they will try tell you a right way to revise.
Do whatever you feel is best - i.e, if you can't sit and read for ages, don't sit and read. Try taking notes instead, and remembering those notes instead of reading through your own textbooks that you might find boring.
I found revision cards to be a big help too, cos they aren't huge daunting pages of text. Simplified notes on a small postcard size note helped me to remember short bursts of info rather than pages at a time, and the size of them didn't put me off revision like reading a massive book would.
Steer clear of the PC. Too many distractions.
Past exams are also a good way to revise. That way you can get your teacher to mark them, and find out how they want you to answer the question. The fundamental thing about A Levels is knowing your stuff. I know it sounds simple and bog standard in terms of an essay, but you absolutely need to know the facts. Get the facts in your answer and you will get the marks. This is of course if you are taking History/Psychology etc.
For things like English, it's best to look at the question. Underneath it is usually a list of bullet points, which tell you how to go about answering the question. The best thing to do is practice these questions over and over again, until you can answer them in order, perfectly, each time, and also practice keeping to the question.
It all depends on what subjects you do for A level but those are my tips. Dunno if they're of any help.
Going to start the hardcore revision this week now.