What settings on your camera should you use when taking photos in dark environments?

Such as these http://browse.deviantart.com/?qh=§ion=&global=1&q=ifc+roof#/d2ux6yt

when you are taking photos of a model in that type of environment where it is dark but is lit up by light, what are the best settings on your DSLR to use (i have a nikon D90) in order to create interesting lighting?

Of a model?

I suggest shooting in "A" mode, and set your ISO to around 800 or higher to prevent blur.

To create interesting lighting, you must seek interesting lighting, or create your own. Lighting can't be modified in-camera (nor in photoshop).

Use a tripod. Turn off vibration compensation. ISO as low as possible. Smallest aperture your lens will accept. (Largest f-number) Experiment with shutter speed… Maybe as few as 15 secs to as long as minutes long. (My Milwaukee skyline panorama was a series of 7 shots, each 15 secs long. I have another of suspension bridge cables which was a 3 min long shot.)

www.flickr.com/photos/LeroyPK