Underexpose your pictures for a darker mood
Traditionally, getting a “good exposure” means getting a picture that has a nice even spectrum of light from the dark shadows to the upper highlights.
Sometimes you can create moods by intentionally underexposing your subject. The idea is not to underexpose too much, you want to see detail, but you’re deemphasizing the highlights to create a different mood. Maybe this is quiet, maybe its sad, maybe it is dramatic.
You also need to pay very close attention to the scene you are shooting as this won’t just work with anything you point your camera towards. For example a bright sunny day will just look underexposed. But maybe a still life with minimal lighting, a sunset, a portrait, or even a texture would speak more clearly by backing the exposure off a stop or two.