An old trick is to view your subject through a dark green filter- that gives you an idea of how the subject will look in black and white. Another way is to look in a brown filter, it gove similar effect but better suitable for street photography.
If you like to shoot black and white, try to use a green filter on the camera when working out of doors. It gives a healthy flesh tome and lightens dark green foliage so that dark suits and hair does not merge with the background. A light yellow filter when used in a (flash) portrait set up, produces pearly skin tones in portraits of the bride- combine that with a bit of soft focus and you have a wonderful effect.