Don't pull too hard on the feet when you use the bar /broomstick method , else the head will come off .
I've been there got the messy jeans. If the bar is fully stood on and it's on a flat a hard surface it often separates the neck without any pulling so watch what is happening at your feet .
Doing the neck method remove any rings you might have on your hands .
Eeven though I used to be nearly six foot tall with an arm set to suit and shoild have been able to do a simple spinal /neck cord severance I always found that holding feet in left hand between the ring and middle finger with the hand facing backwards and the neck from just behind the ears between the index and middle fingers of the right hand , with the hand pointing again behing you , place the remaing part of the neck across the knee of your straight right leg then pull the legs of the bird with the left hand and push the right hand down to the right rear . Only occasionally did I pull the head off . Keeping the bird close to the body helps to stop you getting battered by flapping wings as you invert the bird.
In all cases the nerves of the bird will frequently continue to operate for a few seconds even though it is completely dead so watch out for legs kicking and scratching you or wings flapping like it is alive and demented for six seconds or so.
I think there is a set of youtube clips of it