Light direction
Light direction is the angle that the source of light comes from in relation to objects. The same object lit from different directions can look absolutely different and bring out different emotions. For example, a face lit up from the bottom seems dramatic and even intimidating. By changing the light direction, you can highlight the object, enhance the illusion of depth, and intensify details that you find essential.
Pro Tip: Don't forget about the balance — when you bring some parts to light, mute the other features or submerge them into darkness completely.