Curl the ball into the string before fastening the string with a tuning peg. Slide the ball into the hole and gently pull up on the string while pressing in the bridge pin. This will lock the string into place.
Slide the string through the tuning key post and pull it somewhat tight, leaving enough slack to fit your fist under the string.
Wrap the string around the backside of the tuning key post, under itself, and then over the top of the string. This knot will lock it into place.
Use a peg winder to turn the string counterclockwise. Make sure to apply light pressure on top of the string to ensure that it wraps below the tuning key post.
Cut the extra slack from the tuning peg with a pair of small pliers.