practice jumping in place as high as possible & tuck ur knees n2 ur gut & land with ur knees fully bent. Then work on squats aswell the 2 muscles u need 2build r ur biceps triceps & glutes & calves... now also practice tucking ur bars & pushing them forward more,
& work on ur timing 4 ur jumps, especially on flat, try stacking objects up & hopping it & commit!!!