Jump up onto the bar and engage your shoulders so that you are actively pressing into the bar. Pull through your chest and form the hollow position while hanging. Hold for a few seconds and relax. Arch through the upper back into the opposing position and hold for a few seconds. Once you are comfortable with the two, start transitioning back and forth.
Please read the originial post here: https://www.industrial-athletics.com/building-power-kipping-pull-ups/