Arrond: the best thing for you to do is buy as much ammo as you can and shoot a lot. If you start flinching, stop for couple days, then shoot some more. That's the best way to learn to shoot. A good coach can help too. But you are getting no where if someone else sights in your rifle, you will still have large groups.
Sighting in does not affect group size, it only affects where the group appears on the target. Group size is affected by the skill of the shooter. So you need to develop your skill. All else doesn't matter.
Cogito, ergo armatum sum