BW... in some of my other responses you will see that I am a big proponent of practice. It is one of the reasons that I recommend reloading because it allows you to shoot more for less. I normally start at what I am least good at. So when I get a chance I am usually in a standing position shooting to 100 yds. I have not managed to find trees that move to where I need them in order to make a rest to shoot off of. Funny how that is.
Then I move to knee or sitting. Most can shoot prone so I don't work that one as much. Two things that I work all the time is breathing and trigger control.
And there in lies the start of it all... the confidence to make good shot placement.