Jack, that's a great graphic about sight focus. Quite useful.

Of all the fundamentals, I think that the most important are:

1 - Sight alignment (more important than a perfect sight picture)
2 - Trigger control

If you get the sight alignment right, aim for an on-target sight picture and then don't disturb it with your trigger pull, you should become more consistent.

While breath control can be an issue, I think focusing on the above things will contribute more to consistency.

This isn't easy. It takes time to practice these skills. I guess that's why I reload.

All the fundamentals apply when shooting inexpensive .22 caliber ammo. I practice by first shooting a couple of boxes of .22LR, then moving on to 9mm and .45 (which adds dealing with recoil).

Marc