Most important:
Turtles and box turtles should be kept upright at all times.
They should be held with both hand around their shell, out of reach of their jaws if they are not friendly.
Do not:
Poke a turtle that is hiding. Wait for it to come out on its own.
Roll a roll a turtle on the floor.
Leave a turtle upside down for more than a few seconds when inspecting the bottom shell, and do not turn upside down unless necessary.
Drop the turtle or put it down roughly.
Kick or step on a turtle.