Sore shoulders?

Students sometimes get sore shoulders. Usually this stems from over-stretching.

Aim to drop the elbows; not just lower them, but actually feel the weight and allow them to hang.
Rather than stretch at all, feel what your natural range is and stay within 70% of that.

Your frame may look and feel much smaller, but the emphasis will be taken from the shoulders and arms, and placed back upon the centre; the muscles around the waist, hips, groin, sacrum and spine.

Make sure that you remember that muscles move your body, not bones. Stretch too far and the joints will be sprained. Keep the joints loose and open, relaxed.