See if you have any NRA Certified Rifle Instructors in your area. Some charge for their services and some do not.
Here are some of the common mistakes people make with long guns and handguns.
Changing the grip between shots or moving the hands between shots.
Changing the grip pressure during the shot.
Too much or too little trigger finger.
Poor alignment of the firearm to the strong hand and body.
Inconsistent pressure of the long gun against the shoulder.
Inconsistent and poor balance/stance.
Not doing breath control.
Not doing follow through.
Moving the head right after a shot to see POI - not doing follow through.
Moving the firearm right after a shot to see POI - not doing follow through.
Not focusing on the front sight until follow through is completed.
Moving the trigger finger after a shot before follow through is completed. The pressure of the trigger finger on the trigger should not change after a shot until follow through has been completed.
Incorrect sight alignment or sight picture.
Here is a link to shooting a rifle. One thing the shooter does that you should NOT do is he moves his hands between shots. This changes your grip, and has the potential to reduce accuracy.
Shooting sports can help to develop skills, BUT
for many it also produces bad habits. Those bad habits could be very costly in a real life situation. Your muzzle should not go into the plane of a port. Some competitors will also stand in the middle of a doorway and shoot. It may take some time off for competition, but it is a very bad habit. What shooters do in practice or competition is what they are more likely to do in a real life situation. If your instructors have good credentials and are teaching sound techniques, I suggest sticking with what they are teaching you. I would also look for second opinions from other instructors to help ensure you are receiving sound advice.
Here is a clip of Todd Jarrett. He starts out with a 1911 and moves to an AR. He covers shooting through a port.