That's good advice, Brimwood Farm. IMHO, from the bird's point of view, the only thing you can really do wrong is to be too timid. Yes, it's gross to pull their heads off, but it's better that way than to not use enough force. So I'd agree, use a round broomstick or metal bar (nothing thicker), and do it on hard ground too. Place the bar over over the back of the head at the base of the skull, hold it down with both of your feet and pull upwards on the bird's feet. You'll feel the neck give, then a split second later it will start to flap its wings (the typical 'headless chicken' response). Once you get the hang of it this way, there's usually no blood, but the bird bleeds out into the cavity you made when you stretched the neck. However, the only way to know when you've got it right is to overdo it a few times (pulling the head off if it comes to that) and then learn from there.