Good coaching from Rick Welch and Rod Jenkins have eliminated the worst of my bad habits, allowing more subtle ones to be uncovered.
The one I'm struggling with now is string torque. I'm not even sure if that is the right word for it, but when I draw the bow, my string hand tends to want to hold the string at a slightly different angle than my bow hand wants to hold the bow, creating a torqueing force on the string. This is usually combined with my string hand not being totally relaxed. This usually throws the shot off to the left, as my string hand seems to want to hold the bow in a more vertical position than my bow hand does.
To combat this, I try to hold the bow in a loose grip with just my thumb and forefinger holding the bow, so the bow can sort of swivel around to match the angle of my string hand. At the same time, I try to get my string hand as relaxed as possible.
The problem is that it's not really obvious to me that I'm torqueing the string or if my string hand is relaxed, so sometimes the first indication I have that I'm doing it is when the arrow goes left. Then if I work at it for another shot or two, I can get my string hand relaxed and the bow lined up with the string, and the arrows start going straight again.
Another problem is that I would like to be able to shoot longbows, and this loose thumb and forefinger grip doesn't work so well on a longbow. If I heal down on a longbow as recommended by Howard Hill, this problem gets worse, as it is even harder for me to feel whether I'm torqueing the string or not.
Any ideas for working on this?