Cheerleading tryout help!!!?

okay so i'm going to be a sophomore next year and i'm trying out for cheerleading. i really want to make JV cheer. i have tryouts next week. i'm trying out as a flyer for stunting (its my first time as a flyer). I have a half down but i cannot cradle,twist down, or anything advance. I have no tumbling, and my jumps suck. I can pick up dance and the cheer part really good. How can i get my jumps good fast? And what are some good flyer tips? What are things judges would like to see? How should my attitude be? Should i work on anything else? Thank you!