Its important for you as a Dom to know when to punish and how to punish. Me as a Dom I dont punish from the first time; I believe in negotiations; believe in persuation. I would punish my girl after telling her that she is going to be punished for the following reasons and I should persue her with this. Also there is a way of punishment. Actually dont go that rough at the very beginning because her body will get shocked so do it rough but step by step. Tie her up and punish her on the punishment spot only. Let her count and apologize after each count. After you are done with your punishment hug her before you start your aftercare treatment.
After care treatment is the most important thing. Its essential than the punishment itself. Let the aftercare treatment takes time more than the punishment time.
I prefer to have sex after this treatment. I prefer romantic sex as a kind of reward