Oh our 'ground rules' these are the rules we put in place it may have insight for you.

Ask if about handling the snake
Wash your hands before with soap...
wait for us (parent) to remove the snake from the enclosure (never remove the snake alone!)
Sit down and we will give the snake to you (safer for the snake)
never drape the snake over the back of your neck across the shoulder is fine or in the lap. (this is not so much concern about the ball python but other snakes it forms a good habit)
Do not take the snake away from supervision (snakes can get into and under all kinds of thing if you are not paying attention)
No kissing the snake.
when the snake has had enough ask to have it returned even if you don't want to. (they can become stressed and we must be cognizant of the animals need over our wishes)
Let us know when you need to return the snake wait until supervised.
spot check the enclosure water/wastes/objects (every time we remove the snake we check to make sure the water is clean and full there is not poop pee and that nothing fell into the enclosure that should not be there)
Check to make sure the enclosure is secured
Check again to make sure it is secured (We check and I have the child check too again good practices)
Wash our hands (we do this together it is part of our ritual) with soap and wash then not just get them wet...