Get there an hour before, do some light jogging and spend the time stretching, both lower body, core and upper body. As you go to the ring, or to the runway, focus your thoughts, think of only the task at hand, and relax. Take a deep breath, focus and begin your throw. To develop your mental skills, spend five minutes every night before going to sleep telling yourself that you will throw or jump your best in your next competition. Tell yourself that I am the smoothest thrower that I can be.
Competition is really self discovery.
Perhaps you will find out that you are not a first throw athlete, that you develop over the competition, and that your last throw is your best.