Don't use a cone for a start off!!!!! That poor goose suffered dreadfully!!!!
Anyhoo.....Muntjac is dictating whilst I type....
Prepare a 1/2 inch thick rope about a yard long by tying a loop in it, suspend this from a joist in the shed, garage or similar. When it's dark, select your goose, talking quietly, pick it up by putting your arms over the wings and keeping it close to your body. Quietly walk out to where you have prepared the rope....talking and stroking the bird to keep it calm. If you are unable to do the next step on your own, get someone to help, but make sure you keep yourselves very calm 'cos this transfers to the bird.........get them to make a smaller loop in the suspended rope and place this over their legs....between the first knuckle and the web.The bird's head should be level with just below your hip. The bird should still be calm. Take your right hand behind the bird's skull and your left hand holding the head ......the bird should be placed near your right hip. By taking your body weight back and down and bending your knees and keeping a very tight hold of the bird this should break the neck. It has to be done in a very quick but smooth motion. It may help to actually apply some arm pressure on the downward stroke if you are not very strong but keep your arms locked. When you feel the head part from the neck ,just continue on a little bit more to make sure the spinal cord snaps. move aside very quickly as the wings will flap wildly although the bird will be dead, but the force will hurt! You could always practice this with a rolled-up sack in the loop beforehand if you don't feel too confident about it. Pressure and speed is the key to get the job done properly. This also applies to turkeys or any other big bird.
In Munt's opinion, you should let the wings flap to take away any blood that could pool in the flesh.
Good luck!!