Instructions
Hold your pencil with your thumb, index and middle fingers. Your index and middle fingers should be behind the pencil, and the thumb in front of it. The grip is similar to holding a pencil to write, but the positioning is different.
Place your thumb about halfway between the eraser and the middle of the pencil. Your middle finger should rest right at the middle of the pencil, and your index finger should be right on the other side of the pencil from your thumb, or slightly closer to the eraser.
Push with your middle finger, and straighten your index finger. This will push the pencil around your thumb while getting your index finger out of the way, so the pencil doesn't hit it on its way around.
Grasp the pencil with your index finger when after the first end spins past. This will trap it between your two fingers.
Turn the pencil over with your thumb and index finger to return the pencil to the starting position. You may need to push one end down with your middle finger to start the pencil turning.