Do you wear some type of gloves when doing this to prevent the scent of your hands from getting on the glands?
I'm very cautious about touching the actual glad itself by cutting at leas a half inch of skin all the way around it so you can handle it without touching the gland itself.
When I'm done I'll have about a 2" square with the tarsal gland in the center of it. As long as you stay away from the dark brown oily spot, you'll be ok.