Working with models is an essential part of the fine art tradition, whether for figurative or portrait work - despite photography's tremendous helpfulness in providing easy access to reference, it cannot take the place of the variety of tones and expressions encountered in the presence of a living person.
Working with models can be challenging, though, for many reasons: getting them to hold the pose is generally the first, but there are many others as well, such as finding a pose that looks natural and being aware of their comfort level (if they're very uncomfortable over the course of a long pose, it will show up eventually in the painting!) Thomas Couture, though not well-known today, was a successful and well-respected portraitist and art instructor in the late 1800s and he wrote a book full of useful advice to young art students, including how to successfully work with models and capture their unique attributes. Here is some of his advice, along some examples of his lively portrait work:
"If you wish (to draw) models, it is better to surprise them and draw when they are not aware you are doing so. Lines drawn rapidly, observation and notes taken under the fire of first impression will guide you. . .
You need to have sympathy and love for what ever is living; movement, intelligence, passion, and thought; follow all these marvels of life as the hunter follows his game.
See that beautiful child overheated by play; the lovely tints of his face, the beautiful disorder of his hair, and the sun which throws over all that golden light. Quick, your sketch-book, make your lines and notes, that is sufficient; be satisfied, you have made a good study.
If after you have sketched a good movement, or a natural pose, you can obtain a sitting from the person observed, you will then be able to make a perfect study, but you must only use the model, in order to assist you in carrying out your first impression. This must come from yourself; one is able to do well only what one can understand."
