Hi Coleen,
I think a good think to do in preparation is to write down how you plan to perform well in the next competition and how you want to carry yourself and what attitude you want to have going into the competition. Plan how you are going to manage if something like you loose your stirrup happens. And also plan what you will do after the competition. The more crystal clear you are before and the more prepared you are for anything that can go wrong the more stress you eliminate.
Alex.