I use to do a lot of coaching when I was active in bow tournaments and owned my archery pro shop..
A couple little tricks for shooting a bow.
Hitting your arm,there are two reasons for this ,being over bowed ,to much weight and you cave into the string
the second is not rolling your elbow out. Try this extend your arm have hand in the position you would hold your bow now try to roll your elbow out so you have more string clearance . you cant do it, now walk up hold the edge of a door with your hand in the same position as before, put a little weight against your hand now roll your elbow.,it will move just fine now. since this doesnt work unless you have pressure against your hand it is something we are not use to so you have to train yourself to roll that elbow out after you have pressure against your hand pulling the bow. It helps a lot
Grip of a bow should be relaxed not gripped tightly ,but you can not shoot open handed are catch the bow with finger movements, open handed you have to have a bow sling. Your mind will start anticipating the shot and grab the bow in that splity second before you rewlease disturbing your hold on the target.
The simplest way I have ever taught anyone to shoot a finger release ,is to not turn loose of the string ,just point the top finger at the target,the other two fingers will follow that top one and let the string go,if you try to open the hand you wind up plucking the string.
This is set in stoneeeeeeeeeeeeee
If you do the same thing every time ,no matter how bad the form you will hit in the same hole.
Ron