Never done it myself, but I am guessing a google search with the term 'low key photography' would get you the results you're looking for. I know it's a technique using off camera strobe, but other than that, I've never really looked into it.
Dark Background, Dark Clothing, Light VERY Close to the subject. We do a lot of it at our portrait studio. The thing that seperates great low key from bad low key is having additional accent lighting for the hair or what is called a rim light.
Most times it is done with a single light, IE your key light.
There is a difference between Low Key light, and a bad exposure.
Like mentioned above, pulling your light source close to your subject is a great way to start. I use a hot light, or a constant light (Wescott TD5) for this, and put it just out of cameras view.
The light and shadows should give your subject definition, it should isolate it, and make it a bit more dramatic.
Look at the shadows because those will reveal where the light was and if it was modified or not.
Sharp edged shadows means the light source was small and not modified.
Shadows that have no edge and are very soft, were made by large appearing light sources which means modified light.
Bouncing light into a 60 inch umbrella, off a ceiling, off a side wall, or making the light go through a big diffuser panel makes the light source appear to be 60 very big and the shadows wrap around and get very soft.
Fancy & Expensive light setups are not necessary, look at what I used just trying out something new a few weeks ago...
A flashlight from the right, clamped onto the furnace, a black towel as a background and black plastic sheets I had laying around.
And got this...cloned out the wooden stand inside the skull, smoothed out the tape used to hold on the skull crown, and made it B&W. Not "pro" but it's a good start for DIY materials.
Be creative and try things, you'll learn a lot by experimenting!