With a brand new golfer we discuss the importance of the grip and the face that the hands are the only body parts that touch the golf club. That and the fact that the face is how all shots start, makes it very important to get the hands in a position that promotes a square club face.
When I asses the swing of an experienced player I look at the grip and aim and goals of the player. If the club face is inconsistent we discuss the grip. If the club face is consistent I take a picture of the grip. I tell the player to develop a routine that produces this grip every time.