Set the incline bench to 60-70 degrees. Gently extend the thoracic spine and slightly depress the scapula. Start with the shoulders at 90 degrees of flexion. Lift the arms to achieve an abduction angle of 150-170 degrees. Lower slowly and repeat (thumbs in the direction of movement). Note that the shoulders should not come all the way down to the bench, but only to 90 degrees, and maintain the shoulder depression and thoracic extension. Source: https://youtu.be/iX5PGxGSWN4?feature=shared