Before you shoot:
1: Take a breath and release it.
2: Do not breath again just yet!
3: Aim and release the shot.
4: Start breathing again!!
Works every time for me.
When you are not breathing, this takes away the movements made by the chest, neck and shoulder muscles while breathing, thereby making your aim and subsequent shot as steady as possible.
To firther explain this, with an unloaded rifle, take aim and look through your sights or scope while breathing and you will see your aim is all over the place?
Now try exactly the same procedure while NOT breathing - and what do you see?
Like i say, works every time for me.
HTH
One Shot.
"Some can brighten a room when they enter it . . . others, can do so when they leave it . . ."