Filming With Natural Light
When I don't have much offered to me in the area of lighting equipment, I start searching/studying my locations options. You find your self directing your talent around the locations natural light setup. It is good to come in to your project knowing the feel you are looking for ahead of time. You won't regret if you studying the feel you are going for at the start, having reference material to fall back on. For me Film Noir is great because it forces you to connect with your protagonist. Bring him or her in and out of the shadows is crucial to starting to connect/relating to the hero. How can we appreciate the bright side of life if we haven't experienced loss and pain.
When Using Artificial Light
If you are using artificial light, Make sure you are complementing the natural. If you are needing more control, eliminate as many practical lights as you can and shape it your self. The true art is the mixing of both practical and artificial light.