The tip we got that gave the biggest results was drag the drive toe like it was an anchor it kills the drive but hard to detect
Sorry late to the thread. Besides all the nice cues that everyone provided here sometimes it's in the process. When I start my kids the start at 5' getting the spin right and relaying the spin they are seeing to me. Then when the are at 80% perfection with it they can move back to 10' and then 15', 25' ect. Then they are on the mound trying to get the spin right. Not location, not necessarily speed just spin. When they got that right around 80% then we work on location and speed in the sense where maybe they need to stiffen the fingers or release next to the hip instead of out front. They will usually throw it pretty consistently by then. As they are getting better we start eliminating some of the close up drills from the lesson. They sometimes will slip and lose it for a few weeks so we go back up close and go through progressions again. Here is a video that can help with visuals. At 1:50 mark is a good spin and the next clip is a 10 year that had 25 strikeouts yesterday throwing that change (drop 3rds ). Press the space bar and period or comma to slow mo it.
Cue that worked for my kid was imagine dumping a glass of water out in front (ie 3 o'clock and thumb down) and imagine dumping a glass of water out behind you (ie 9 o'clock and thumb down). Then we used the finish at the glove side hip to bring it down or finish glove side shoulder to bring it up depending on where she was missing. The key in my opinion is getting that thumb pointed down at 9 o'clock. I think the purpose of turning down of the thumb at the 3 o'clock position aids in creating arm lockout which is a definite speed killer. Just my 2 cents and what worked for my DD.