Performing the: A Step-by-Step Tutorial One Arm Chin-Up
Pull your shoulder blade down and back before you start to pull yourself up, this is to engage the correct muscles and protect your shoulder from injury.
Slowly pull your body upwards until your chin is above the bar, try to keep your body as straight as possible and avoid swinging.
Hold the position for a moment at the top, with your chin above the bar, then slowly lower yourself back down to the starting position.
Repeat this motion for a set number of repetitions, then switch to the other arm and perform the same number of repetitions.