Revision is the obvious answer. Different types of a revision approaches are also highly recommended.
Behind revision and the retention of knowledge also is technique, the ability to understand what a question is specifically asking for and what you can do to make the answer crystal clear and meet the criteria of even the most jaded and grumpiest of examiners.
If you’ve put the hours in, you’ll reap the rewards, but finally it’s worth remembering that exercise, eating well and sleeping well all go a long way as well.
The little drips of progress along with choices that ensure your physically and mentally at your best is key to getting the best out of yourself during an exam or an exam season.
It all comes down to discipline and the choices you make.