Just buy one of those self prep books in the bookstore, and about 2-3 weeks before the test, sit yourself down and go through a little bit of the book every night. Then when the test day comes, I can't stress this enough but it's all about attitude.
When you go in there and take the test, never doubt your answers but instead feel confidence that all your answers are based on your best judgement and you feel are correct. You'll find yourself going through the questions at a much faster rate and never once think about how your test score is going to be during the test. That just screws you up.
Just focus on the test, go through each question, think about it and make the best judgement...then MOVE ON. Don't ponder. If you find youself playing with your pencil during a question, you've spend too much time. Good Luck.