I’m actually in the process of learning to use a stick myself. I have played on a stick occasionally a few times in the past but since i have never owned one until now i was never able to grow into it.
I have 2 suggestions that have been helping me a bit:
1.) Remember to go back to neutral as much as possible.
2.) Don’t be really wild with the stick. Odds are if you are missing inputs it is because you are doing them wrong. Learn how to do all the motions slowly and precisely. My brother had this problem, he would really go crazy with the stick and end up missing simple things or accidentally jumping. If you want to do a hadouken for instance, dont just ride the gate and wildly fling your hand really fast. Make sure you start at neutral, move down, down-forward, forward and return to neutral.
edit: also. on my first few days i would miss abel’s HCB+P command grab because i wasn’t going all the way back, i was riding the gate and ending in down-back… It takes a little while to get a feeling for where each direction is. Like you may try to go back but accidentally go up too far and jump backwards instead. After a little while he will get a feeling for exactly where each direction is which will definitely help.
For me its important to remember that as long as the buttons work, they shouldn’t take too much mental focus to use correctly. The biggest difference between a pad and the stick is switching from d-pad to stick motions. So just learn everything in slow motion and work your way up…
For your friend, as with me, its just going to take time and practice. As of now im much worse with a stick than with a pad, because i learned ST and 3s on pads. But i know i’ll get better in a few weeks. Just dont get discouraged if you accidentally miss an input and lose.