Be bold, is the key.
If right-handed, tuck hen comfortably under left arm. Hold her head, with your right hand above it, and your fore and middle fingers either side of her head. Then a strong and sharp push away and twist.
If you're worried about hand-strength, use a broomstick. Lie the hen with her head and neck on the ground, put the broomstick over her neck, and stand with your feet on the stick, either side of her. Grab a foot securely in each hand, and pull up hard. This is a good method for bigger things too, which you couldn't manage with the twist and pull method.
They don't seem to stress about the neck-under-the-broomstick stage, oddly, and then it's over before they know it.
Then pour yourself a large glass of wine
