Shoulderstand on feet to handstand on hands is not only one of the easiest H2H transitions, it is also a got calibration excersice. Thus, it's part of many advanced acrobats warm up and calibtration routine. The flyer starts in shoulderstand on feet and slowly goes to a handstand position by opening the shoulders. From there the base extrends the arms.
The base starts opening your shoulders. Keep your shoulders relaxed so that it is easy for the base to open your shoulders.
Take care that you do not arch in the handstand position.
When in shoulderstand on feet the weight should be just on your toes and not on the whole foot.
You can do this in a wide circle or in a straight line movement).
The handstand line of the flyer should be stacked in one line over your shoulders and hands.
The weight should be on the front of your hands. Keep the wrists at about an angle of 45 degrees. Do not squeeze the hands of your partner.
Stand on the side or the back of the flyer and spot the hips of the flyer.