Do your characters smile a lot? Mine do, and I've found that I need a new way of showing their happiness. There are different reasons and types of smiles, but this will cover general happiness.
The following is a combination of information I found on Emotional Competency and Physiology of Facial Expressions.
Synonyms: amusement, bliss, happiness, joyous, carefree, jubilant, exultant, cheerful, playful, amused, fun, glad, gay, gleeful, jolly, jovial, delighted, enjoyment, euphoric, ecstatic, thrilled, elated, enraptured, comfort, contentment, harmony, satisfaction, and triumphant.
What does it look like?
True joy is expressed by the Duchenne smile where the involuntary muscles around the eye orbit are fully involved. Friendliness, but not heartfelt joy, is expressed by the “Pan Am” smile, which does not reshape the eyes or lift the cheeks.
The Duchenne smile expresses true joy with these distinctive features:
*A smile, raising the lips at each corner of the mouth, and
*The muscle that circles the eye contracts. This:
*pulls down the eyebrows and the skin below the eyebrows,
*pulls up the skin below the eye, and
*raises the cheeks.
The Pan Am smile expresses friendliness but not joy with a smile lacking the contracted eye orbit muscle. It signals appeasement.
Example in writing:
Telling--She smiled at him.
Showing--The corners of her lips jumped upward at the sight of him, and her eyes sparkled in the light.