Look at how much room the frame gives the subject and what that space contributes to the portrait. Read the frame from the outside in and see whether that changes which detail seems most important.

A portrait to view as a complete composition
A frame to linger over
A gallery portrait for a closer look at composition
From this set of portraits
A gallery portrait from the current selection
An individual frame from the gallery
A portrait view of a person
A frame to view in context