i would say practice a whole lot like as much as you can. And i had the same problem when i first started getting my tuck and then someone told me that if i reach straight up real high and as hard as i can ill go straight up and my tuck would b higher. I think you should try that. Another thing you can try is speeding up your tumbling. Maybe your not getting enough power in you BHS to get a high tuck. I find that if you tumble on the palms of your hands only then your tumbling is alot faster and you have a higher rebound! well i hope that helped, if not then srry i tried!
