Help with the show (First)?

i only have two weeks left before i enter my first riding show on a grey 13 -14 hh horse. we are entering the clear round jumping, gymkhana and the best combination. what things should i do to keep my pony under control when jumping as she frequently takes off, what would help with winning the judges over in the best combination and how to get the horse going in the gymkhana but stop when we near a pole. all tips are welcome :)