Even though I might mention on this topic in the past, I would repeat it here. Regarding how to handle a paddle or a bug key.
Our hand/fingers should be as if it were grasping something fragile like an egg. The finger joints as well as hand joint should be relaxed in half flexion position. It is in order to have the fist respond promptly to any required movements. If the fist is in tension with extended joints, it won't respond to any requirement quick enough.
This form of fist is the same as that holding a string instrument bow. We need to have the hand and arm move quickly as well as flexibly in string instrument performance. The same form is quite necessary for that purpose.
If you find it difficult to control especially dots, consider of the form of the fist holding a paddle or a bug key. Is it ready to respond to required movements?
Just for an information.