Be Gentle and Light First
From my experience when we begin Chī Sáu 黐手 we always start off being gentle, light and quiet. Chī Sáu is not fighting. My Sīfú 師父, Grandmaster Ip Chun 葉準師父, always says Chī Sáu is partner training where we learn the Wing Chun way and skill. It is preparing us to fight in the future. So in Wing Chun we need to be calm, quiet and gentle before the fight, until we know the situation and what the opponent is going to do to us. The exception is if the attack is already coming before we know and then we just do whatever skill we need in that situation.
So of course the skill can be used in fighting but Chī Sáu is training and so we learn to read our opponent’s energy. Every time our opponent tries something we can change the situation so that it is beneficial for us. For example, if the opponent tries to push down our Tāan Sáu 攤手, we can let go and change to Fuhk Sáu 伏手 and so we do not need to support his strength. If our opponent pushes strongly with his Tāan Sáu, coming to our Centre, we can step to the side and change our Centre and so we do not need to face the threat and power of their Tāan Sáu. If the opponent punches us we can change to Wuh Sáu 護手, extending it forward to block their hand. Of course we do not always need to defend and we can also use situation to attack.