To paint a face with a particular expression, I usually hold a mirror next to me and mimic the expression. Having this reference on hand, which I can see from many angles, helps a lot. A smile, because of its characteristic of spontaneity, is very difficult to paint and is often in danger of looking fake, not very expressive, or wicked. I’ll try to do my best!
Touching my face also helps me to understand what’s happening when I laugh. When my mouth first widens, it opens in a crescent, the lips become thinner and the teeth are revealed (usually only the top ones, but if the smile is very expressive you can also see the lower ones).
The cheeks become rounded and they rise near the eyes, creating two folds around the mouth. The eyes become halfclosed and widen. Sometimes the nose curls or widens slightly, too. Finally, the head usually tilts a bit. I keep these characteristics in mind as I prepare a sketch. I have to highlight these features using colour.
I add a shadow under the lower eyelid to the narrowed eyes. On the cheeks I add a touch of light to point out the roundness. I pay attention to the folds on the sides of the mouth, because if they’re too dark and large they make the character appear very old. But they are essential for a beaming smile.
I can emphasise a character’s beaming smile by using bright light along with light shadows.
When a character has a beaming smile, many areas of the face are affected. Try to consider them all as you paint.