Simple connected movements will do. Sore shoulders come fom trying to fight against energy. You should not lift the Bong sau , it should spiral forward with minimal shoulder use. Try to use the concept of neutralizing force along the tangent of a circle. The circle can be horizontal, vertical or diagonal.
Many people apply their energy at the wrong moment.
Try to feel when is the best time to apply your energy. Try to feel when the opponent's energy starts up. Don't push the force away. When nearly all students apply the Pak sau , the Bong sau , the Fook sau , the PoPai , they are pushing the force away. They are scared of the force, they want to get rid of that force.