Get Comfortable with YOUR Rifle
Most modern rifles are more far accurate that the operator who is pulling the trigger. The best way to improve your groups is to shoot a lot of rounds, preferably with your own rifle.
Issues like flinching tend to subside more and more with each live round you fire.
Even dry firing can improve your trigger feel and form, if you can’t get to the range often. There are dummy rounds for most calibers you can use.
The more you get comfortable with your gun, it’s action, trigger, etc., the tighter your groups will get. The key is repetition and it’s really maddeningly simple. This is also way it’s a great idea to select a rifle, scope, and caliber that you enjoy shooting. Lots of folks want the biggest, fastest round available. Few enjoy the recoil or expense however.