The tones and shadows of the face remain dark. Well you want to light dark complexioned faces in a way very similar to black jewelry or obsidian stones. You use reflections and glare rather than fighting it. In fact, you want a little shininess on the face, the exact opposite of pale faces, where you use makeup to dampen the shine. So Side Lighting and Rim Lighting.
Large sources work better than point sources.
Bouncing a 1K into a curved white card for a side light can create a very nice glare off the skin along the neck. Side lights can work off the cheeks. Try some warm gels on one side, and cool gels on the other. For the eyes you want a nice broad softlight, to create a sparkle in the eye, and fill in the sockets a little. This is a challenge if you haven't lit very dark skin before, but its worth the effort, as the results can be incredibly rich and gorgeous.