High contrast, don't shoot high contrast, but crush the blacks in post.
Shadows are ok, in fact they are your friend. In fact, sharp shadows like window blinds, moving fan blades, that short of thing are very signatuire noir.
Pools of light, candle will work well for this. Where the light drops off as you move away from the focus of the frame.
Photos, especially crime scene photos.
Go rent A touch of Evil, Chinatown, etc... some of the classics and watch this weeekend.