To make the most of your revision time you need to do more than sit behind a pile of books cramming information into your head. Revision is a skill and can be learned and improved just like any other skill.
It’s not one particular skill either, there are several tasks your brain has to master to become good at revising. You need to find out about the most effective ways to memorise important facts. Learn how to tackle the different styles of question that will be on your exam paper. Make use of the specification or syllabus your teacher has (should have!) given you. Finally think about your exam strategy, how will you manage nerves, time, stress, difficult questions?
Here are some articles addressing all of these issues to help you get the best results you can.