In endeavouring to capture a likeness in portraiture it is important to remember that each face is a unique problem to solve and there is no formula that will supplant careful observation of your sitter.
However, many of the early problems students face are structural in nature rather than related to likeness. Thankfully these structural problems can be solved by learning a few simple rules about faces.
The first and most fundamental of these ideas is the idea of the head being similar to a box and the structural ‘T shape’ of the face, as pictured above. Following these relationships absolutely key to properly setting up the orientation of the head and is extremely helpful in properly placing the ears in relation to the brow and nose. Avoiding the common error of ‘floating features’.