One body part moves while the rest deliberately stays still – head to the side without the shoulders coming along. That separation is where sharp hits come from.
The reason your hip-hop looks stiff is almost never the move, it's the missing separation: you push the head sideways and the shoulders quietly travel with it. The practice order is head, shoulders, chest, hip – small, slow and in front of a mirror, because here you feel it wrong and see it right. The decisive trick: watch the part that's meant to stay still, not the one that moves. The second classic error is tilting instead of sliding – the head leans rather than gliding along an imaginary rail; keep your eyes level. And a warning that rarely gets said out loud: jerky neck isolations over long stretches can irritate the neck. Small and controlled isn't the beginner version, it's the correct one.