97CV WELCOME!!
As for practice, do you play tennis? Its like hititng the ball, you must FOLLOW THROUGH.
My Job places me in the responsible postion of dispatching wildlife. breaking the neck is fast and efficient. When you do it, do it with alot of gusto!! Yell if you have to. But do it firmly and quickly. I use a metal pipe, 1/2inch diameter and strike quickly just below the base of the skull. If you are unsure of your success, do it again. equal hardness and speed.
I use a Carbon Dioxide chamber to put down other critters, they just go to sleep. But for the meat birds sublection of the head and neck is good.
best to you
Jack