Darkness

Lighting for Digital Film and Television goes into lighting dark scenes specifically.

Lighting Darkness: Interiors

First consider what is going to be visible and what is going to pass through into shadow. Usually you don't want areas of flat black, you want most of the room to "read" with vague shapes and shadows. For areas where the action passes into shadow you'll be wanting an appropriately sized slash of light. This works best if the light looks like it is coming in through a door or a window but unexplained slashes of light are acceptable too. Another method of illuminating a dark interior is with a moonlight kicker which is a kicker at a low level coloured blue for moonlight usually made to cast befitting mullion shadows. A tweak on this method is to light the subject fully and then light the rest of the room with that same moonlight technique, this time using a cookie to break up the light. Finally there may be cases were light will be coming from a practical in the scene. In this case light so as to make it look as if the source is the practical.

Lighting Darkness: Exteriors

This is similar to interiors, usually you just need more light power to illuminate the dark areas so that the camera can read them. In the above photo there is a large amount of fill light as well as light on the subject. The camera of course picks up the light as moonlight and there is just enough light to read the background.

Another huge help is smoke or mist. This gives the blue light almost physical presence in the frame by catching the light and showing it in more obvious areas. Just make sure your light is blue; the Hollywood vernacular we accept as "night".