First, make sure your scope is mounted so that the eye relief allows you to see the full image of the scope without any shading and without have to reposition your cheek from a natural position. To test this, close your eyes, fit the rifle to your shoulder in a manner that feel natural, then open your eyes. You should see the full area of the scope lens. It should feel naturally comfortable without having to strain your neck.
Second, check the comb height of the stock to make sure it provides a natural cheek weld without having to move your head up or down. Again, it should feel natural without having to strain your neck.
Length of pull can be an issue too but for the moment I will exclude that because it's more complicated to adjust on many factory stocks.
Start doing a lot of dry fire (safely) and concentrate on assuming the same cheek well. Then focus on follow through while dry firing at an aim point. I use a small orange dot pasted to a far wall in the basement. The reticle should not move through the shot. Keep both eyes open while squeezing the trigger.
I've found it helpful to have a written list of the process I use to position the rifle consistently including things like trigger position, thumb position, etc.
Since I shoot off shooting cross sticks, my list also includes items like position of my left hand on the sticks, consistent rear pressure, slight tilt of the sticks towards me, etc. So, depending on what shooting aid you use, if any, add those items to your list.
The concept is to develop a consistent process of holding the rifle, pulling the trigger, and following through with a shot. This takes practice, repetitive practice to develop the muscle memory for consistency. Dry firing, in my experience, is an effective way to stay sharp.
