Just relax and take slow deep breaths while your taking the test. Visualize in your mind passing the test over and over before you take the test. This should help you to be calm and help you to do well on the test.
Well... given the fact you're taking a driving test, I guess a shot or two of tequilla would be out of the question, lol... barring that, I would say... just do what you do for anything else: PRACTICE, STUDY, PRACTICE, STUDY, and PRACTICE some more. Don't push it to the point of "burn out, but make sure you are ready and you are confident.
Don't think of it as, "I have to pass this test", think of it as, "I have to learn how to drive". If you are truly competant behind the wheel, than taking a test to prove your skill shouldn't be a problem.
thanx i drive brilliant and conidently just nerves get thy better off me sumtimes! i n'd instructor both believe i will pass if i stick to our techniques ive been using to shut off the neRVES!!!!!!!!!!!