Don’t put your face in a dogs face and don’t your head over a dogs head.
I wasn't aware of that rule back when my sister-in-law owned a German Shepherd for protection. He was trained to kill if necessary, but with family he was a big sweeet darling. Sometimes I would lean down and place my cheek on top of his head. There was never an incident, though. He was a good boy who was very tolerant of my ignorance.