When to punish or not....

The Issue of Punishment: Be consistent and resolute, firm but even-tempered. Your sub may test your limits and resolve -- intentionally or -- more likely -- unintentionally. So if you establish rules, be prepared to enforce them. Which brings up the questions: How do you enforce your rules? Do you punish your submissive? I have four perspectives for you to consider.

You can enforce the rules without punishment. When your sub does something wrong or omits performing a duty, acknowledge it swiftly. For example:

"I thought we agreed that you would always open doors for me."
"I notice you didn't stand when I came to the table."
"Why didn't you pull out my chair for me?"
"Did you forget something?"
It's a matter of taste and style but I handle a sub's errors this way:

I mention the omission
We discus it briefly
Why did she fail?
Is it excusable?
Should the rule be changed?
Is there something different that we can do to make sure it doesn't happen again?
When appropriate she apologizes and tells me she won't do it again
3. I resolve the issue
4. We move on.

It's been my experience that just noting these lapses is more than adequate punishment for a sincere submissive. There's no reason to be overly disappointed, confrontational, or punitive when mentioning these lapses. Don't embarrass your sub in public. He should feel bad enough about it. On the other hand ignoring these lapses will disappoint your submissive. They'll feel you're not invested enough to pay attention.