A Fun Challenge!
My setup consist of a tripod set 18 inches away, 105 macro lens, off camera flash to one side at an 45 degree angle12 inches away, colored shallow plate filled with water and a slow drip from the faucet, place a finger where water drop hits and focus on it, then switch to manual focus. While shooting in manual mode play with different shutter speeds. Any where from 1/60 to 1/250 of a second. Aperture f7 to f10. Get lucky for a drip to hit just right for you. Take lots of shots. I will show a sample of a 1/60th shot.