Horse Question: I am going to go to my first show in a month and...what do I need?

My first show is in September. I am really excited, but want to know everything. I will enter an oppurtunity cl so I need to know about those too. Will there be a hand gallop in my oppurtunity cles (I show hunt seat). Which clothes will I need for hunt seat? Any tips? Experiences? I want to know EVERYTHING!!!