Mistakes happen. When you make a mistake, never try to hide it. Accept the responsibility for it, which may come with consequences.
Let affected parties know as soon as possible. Especially, let your supervisor know as soon as possible. It's often much easier to deal with a mistake earlier rather than later.
Be prepared to put in extra time and effort to make it right.
Learn from it. Don’t waste the mistake by not learning from it.
End-users and customers will often judge the level of our service based on how well we recover from a difficult situation and they are very likely to forgive us when we do it well. Difficult situations or “screw-ups” are opportunities to win supporters for life. Everybody makes mistakes.
The way we deal with our mistakes communicates who we really are.