Getting a slow-pitch softball to break is difficult. Generally, a thrown ball needs some velocity so the spin of the seams on the ball can fight the air, creating a difference of air pressure on one side of the ball, causing the ball to veer off from its original destination. This is known as a "break." A knuckleball, thrown with little to no rotation, is capable of breaking at very slow speeds. The air flowing over the stationary seams creates turbulence and pushes the ball around, making it look as if it is dancing.
File your fingernails with an emory board. Make all the fingernails on your throwing hand flat, approximately 1-millimeter long, so they can dig into the surface of the ball without bending. File them slowly while every so often digging them into a ball.
Put the ball deep in your palm. You should be able to balance the ball on your palm as if you are a waiter carrying a large tray of food to a table.
Curl all the fingers on your throwing hand until the fingernails dig into the surface of the ball. Avoid digging your fingernails into the seams. Fingernails in the seams can "catch" upon release and cause spin.
Stabilize the ball in your palm by placing your thumb underneath the ball. Many people like to put counter-pressure on the ball, balancing out the pressure made by the fingernails.
Pull your hand back and lock your wrist. This motion should stretch the underside of your wrist, more easily seeing the veins. Keep your wrist stiff throughout the throw.
Step toward your target and throw underhand while keeping your wrist stiff.
Provide counter-pressure to the natural urge of the ball to spin out of your hand. Usually the ball spins forward toward the hitter if thrown conventionally so, as you release the ball and the ball wants to spin forward, you must flick your fingernails with just enough force to counteract. Too much force and the ball spins backwards, so practice this pitch often until the ball doesn't spin at all on the way to the plate.