I have just mastered the art of stippling. Here are my tips -
lower feed dogs
set stitch length to 0
if you have option set needle in down position - it prevents unwanted movement when you stop
I did some research and found that it helps to tape a piece of non stick teflon to the machine (cut hole for needle) - it improves the ability to move smoothly. This is sometimes sold as "craft sheets".
Also - watch your tension - I found that bobbin fill works best for your underneath thread.
Good luck