The stage manager is me is coming out and I will give you a practical answer to what you physically need and leave the mental side of the questions to be answered by the athletes and smartasses ;)
Shoes, socks, spanx, uni top, uni bottom, bow. (If you are flying, put these in your carry on. NEVER CHECK THEM!), brace if you need one, cover up
Make up, bobby pins. hairspray, extra elastics, brush/comb, mirror,shout wipes, makeup remover
Extra socks, extra shoelaces, mini glue gun (I always carry one and you wouldn't believe how many times I have used it- usually for a broken bow)
bandaids, liquid bandaid, blister bandaid, tampon, tums, advil, icyhot
ipod and money, and whatever you use to calm your nerves- a book, stuffed animal, luck charm
ID/credentials