Short of using psychic powers or illegal means, you won't be able to predict exactly what will appear on your exam paper. However, you can go prepared. (See Study Tips for some advice on working effectively all term round)

Practice
As part of your revision, look at as many previous exam papers as you can and actually answer the questions in the allotted time.

The night before
Steer clear of all-night revision. Your brain will be frazzled by the time you get to the exam. You're far better off with a good night's sleep. Take the last few hours before bedtime for something relaxing to clear your mind of all those facts (don't worry they will still be there in the morning!)

On the day
Have a good breakfast and whatever you do, don't read your notes on the bus on the way to the exam. Sorry but it's too late for new knowledge and it'll only send you into a panic.

During the exam
Read the question: In fact read all the questions before you start answering any. And then read them again. It sounds obvious but you need to make sure you know exactly what you are being asked. Jot down notes as you go through.
Watch the clock: Work out exactly how much time you can spend on each question, then take off five minutes for reading through and amending.
Write clearly: Presentation is still important, even under timed conditions. And, yes, it always helps if the examiner can read your answer… Make sure your name is on every page.
Relax: I know, easy for us to say, we're not sitting the exam but it really will help if you tackle things as calmly as possible. If you feel yourself panicking, pause, take some deep breaths and start on the question you are most confident about.

After the event
Lengthy post-mortems are a no-no. If you ask other people what they put, it'll only send you into a flying panic if your answer wasn't the same. Patience my friend, you'll find out how you've done soon enough.

Info and advice:

http://www-micro.msb.le.ac.uk/MCQs/exam.html
Advice on all aspects of exam technique

http://www.unn.ac.uk/central/studserv/exam.htm
Tips, advice and further reading

www.bbc.co.uk/radio1/onelife/education/revision/coping.shtml
How to cope on the day