1. Find A Dark Alley
Almost every town has an alley. If you live in a big city, your choices will be numerous. In my town, we have three or four dramatic alleys for photography. What makes a good alley? Narrow walls, interesting brick work, street lamps and gritty textures all make alleys a great place for a portrait.
Working in a narrow space provides a lot of surfaces for flash to rake across, adding depth and drama to your shot. Try putting a flash right behind your subject aimed at his head. This flash will spill onto the alley walls beside him, creating a dramatic look.