Record your serve(slow-mo) with your own cell phone so you can tell which park of your movement needed to be calibrated. With slow-motion video you can spot the nuance and find the right antidote.
Learning to serve can be hard. It’s even harder if one developed muscle memory with the wrong pattern. You want to improve your serve, but the advice you got is too vague.
Try filming your serve pattern with a smartphone (an old iphone 6 will be competent enough with 720p 240fps). Compare your serve pattern with pro’s serve. If you find it hard to recognize the difference, you can consult the pro athlete for advice.
Start recording your tennis serve today. Upload and analyze with pro. Use technology to empower your skills and enjoy a better tennis experience.