Without embarrassment to the child. Jane Murphy suggests that we discipline in private. But do not let the child use the public as a defense. If you have guests over, or you are in a public place, take the child to a private place. Watch what you say.
Reckless words pierce like a sword, but the tongue of the wise brings healing.
Be careful not to break the spirit. Those do more lasting damage than the spanking. Let the rod speak reprovingly, so YOU can speak comfortingly. Follow with instruction about the exact nature of the offense. But make sure they understand what they did wrong and that you have to whip them severely because you love them.