Here's a sketch of some points and training sequences I use with students in their early phases of learning to compete and perform in public. My goal is for students to do their best work when people are listening to them. I seem to get the best results by upholding standards yet keeping personal negative reactions out of the process. Ideally, instead of struggling against failure to mimic, the student is playing from his or her own heart. All but a very few of these points are equally applicable for performing as well as competing.
Competition is a game, to be sure, but it's judged mostly by practicing artists.
Much of what is entertaining for an audience is good in music competition too, especially training and mental preparation of the performer. Teaching the student Anger is for master professionals and ignoramuses. A few learners thrive on it, some are unharmed by it, many are further distracted. However it is important to make the student bear the full consequences of their actions or bad preparation however. I just skip the abuse.