When opening the door for the leader, which hand holds the door and which hand protects the upper edge of the door (to prevent touching the head)

Leaders usually sit in the back seat of the co-pilot or co-pilot.

It's the left door of the car, of course, it's the right hand sliding door and the left hand protecting the head.

Put your hands together with your back to the upper edge.

Be natural and don't be artificial (people can tell at a glance that you are only two years old, and other viewers will resent it)