Getting started with revision can be really difficult at first. At the start of the day I usually write myself goals of what revision I want to complete in the day. I usually revise for an hour and then take a 10 minute break, as breaks are so important or it becomes difficult to remember things.
Make a poster summarising everything for one topic, section or make mind maps. I find that flash cards are extremely helpful as repeating the answers helps you to remember things.
After you've revised quite a bit then have a go at a past paper and make sure you aim your revision towards what you struggled with in the past papers. It's easy to revise easy parts of the course and then ignore the more difficult parts, but if you slowly keep on going over more difficult parts then you begin to understand.