Choose your lights. Start by finding a large low key light. Add smaller, equally bright lights as necessary. Choose a filming location where shadows and lighting variations exist naturally, like a long street with streetlights. These elements will help make your film noir compelling.
Develop a story which uses light and shadow to tell the characters' stories. Create a lighting scheme. Choose which characters will appear in more or less shadow.
Create contrast. Use large, bright lights at 500 watts or over. Add smaller lights or portable floodlights to create alternate light sources. Avoid creating too many grays or off-whites in the film. Film noir is known for its high contrast through dramatic shadows and bright lights. While some grayer scenes are acceptable, watch for scenes that miss capturing that contrast effect.
Before shooting the film, snap black and white photographs of each set and scene to check the lighting. Develop the photos or print them from a computer. Check whether the black is pure pitch black and the whites pure snow white. If you find grays, adjust the aperture and F-stops on your film camera or increase the intensity of the harshest light source.
Light only what you want your viewer to see. Dramatize a shot by filming a shadow of a person running down a dimly lit street or a lone spotlight dragging across a cityscape. Keep the villain in shadow; allow the hero to bask in a glowing light. Switch the lighting throughout the movie to show the dichotomous nature of your characters as a combination of evil and good.
Shoot from provocative angles and light each scene to create a new element in the story. Cast light looking up toward a character's jawline, for instance, or light a villain from behind to produce a silhouette. A beam of harsh light cast directly on a character can be employed to expose her guilt or crime. Filming through venetian blinds or between fence slats creates a striped, suspenseful effect.
Add cigarette smoking to the film, even if it is an electric type of cigarette that produces fake smoke. Allow the white smoke to enter dark scenes and bring characters together or obscure them in puffs of smoke and shadow.