10u DD has been working on flip for about a year. It was bad for first 9 mths. Then we changed our practice routine. Get a bucket of balls and a laundry basket. Put basket behind home plate do 9 oclock drills (up downs) from 5 ft away. Once she makes 5 in basket back up another 5 ft and repeat. at 20ft add windmill with a step and light drag. Same goal to make 5 in basket. At 30 35 and 40ft do full motion. At 40 ft full motion alternate fb cu for 40 or 50 pitches.we were doing this 3 days a week within a week we seen improvements within a mth it was a great pitch. Keep the ball low. Same arm speed and leap as fb. You would prefer she miss low. When she struggles at a given distance go closer have her make a few then move back again. Keep hand tight to hip at release. Follow thru across to opposite shoulder(hillhouse). Use a taped ball for feedback on spin. Do reverse chaining to show her how and when the hand gets backwards. Don't flip the wrist at release. Just let it come out. Good luck its a great pitch when she gets it right.