Basic Drawing Made Amazingly Easy (Made Amazingly Easy Series)

When the head is in a 3/4 view, the center line runs down the face in
a curve. This occurs because the face plate is round, not flat.
The bridge of the nose goes at the intersection where the vertical
and horizontal guidelines cross.
Due to perspective, more of the mouth appears on the near side of
the center line than on the far side of it.