Headroom and Noseroom
Leave the proper amount of noseroom and headroom in front of and above the person you're shooting.
For example, don't have a shot where there's excessive empty space above a person's head. That's just dead space. There should be just a little room above a person's head in a shot.
It's better to have that room below the person's face, space you then could use when you're editing the video to add a title with the person's name.
But don't have the shot too low where you crop the top of the person's head.
And if you're shooting a person standing, don't chop them off at the knees - get their entire body in the shot..
One approach is the rule of thirds:
- one third of the frame should be above the person's eyes
- one third of the frame should be the person's face and shoulder area
- one third of the frame should be the person's lower torso.
And if the person is looking to the side, add space in the direction in which the person is looking, in front of their nose.