How can a brand manage a dent on its reputation?

[Etini]

One thing about sustaining and building a brand is that the brand reputation must be upheld at all points. That's because a negative brand reputation can reduce the sales you make in your business drastically and if not managed well, it can make the business go down.

As a small business, how can we manage our brand reputation to keep it positive at all times? How do we defend our brand reputation against malicious activities from people who are hell bent on destroying our brand reputation? One of the challenges with small businesses is how to protect their brand integrity. How is that achieved?