In lighting, the most important aesthetic quality is mood: the feeling communicated by the lighting design.
You can achieve mood lighting by recipe (Scary: 1. Place spotlight under chin. 2. Aim upward. 3. Add rim light for separation), but the effect may look pretty hokey. To create a mood with light, it's better to understand the four characteristics of all lighting moods and then use your creative instincts to shape them. Those characteristics are brightness, contrast, definition, and realism.
Brightness: High or Low-Key
The overall brightness of a scene is expressed as its "key." A high-key design features bright overall lighting, with shadows used as accents. A low-key design is just the opposite: mostly dark, with bright…