Look at how much room the frame gives the subject and what that space contributes to the portrait. Notice what you register first in a portrait, then look again for details that took longer to stand out.

A selected portrait in the image collection
A portrait in this collection
A person shown in the portrait selection
A selection from the portrait studies
A portrait in the photo series
A portrait to spend a moment with
A study of a figure in a portrait frame
From the gallery sequence