Put down a drop cloth to protect your work area.
Remove all of the cabinet hardware using a screwdriver. Place the hardware together in a location you can remember. Take the cabinet doors off the hinges and set them on the drop cloth.
Sand all the surfaces that you want to paint black using 100-grit sandpaper. This should include the doors as well as the cabinet frames.
Remove all of the sawdust by wiping it away with a clean cloth or sucking it up with a vacuum.
Paint all the surfaces you sanded using black paint and a paintbrush.
Allow the paint to dry thoroughly.
Reattach the hardware and the doors that you removed.
Sand wear spots into the black paint using 100-grit sandpaper. To do this, imagine where your hands go on the cabinets and sand those areas down until you can see glimpses of the white paint showing through.
Tap the surface of the cabinet with a mallet to give it dings and dents to look more distressed.