When the customer makes contact, he does not want a quote. He wants a commitment.
Don't just talk about it, do it.
Making an honest mistake is acceptable. Failing to fix it is not.
Things that are obvious don't need to be talked about. Things that are missing, do.
Occasionally problems will occur. When it happens to your customers, fix the problem fast. Make it your speed and generosity that gets remembered, not the problem.
Your approval gives others the confidence to serve, to learn, to try.