1. Putting a Dilapidated 'Face' Forward

When small businesses don't transact much online business, they often pay little mind to website design and maintenance. We've all seen half-completed templates with "About Us" tabs that lead to "Coming Soon" notations, or blogs that consist of two posts from 2007. Here's the rub: Even if your customers don't make online purchases, you can bet they conduct online research—and an abandoned website makes an unnecessarily bad impression.

2. Losing Your Cool With Angry Customers

No matter how good your product or how excellent your customer service, someone will always write vicious online reviews. Don't engage in a tit-for-tat rebuttal. Doing so won't win your customer back, and it'll look petty and childish to observers on the sideline. If a valid complaint lies beneath the vitriol, respond calmly with a proposed solution. But if the anger is nothing but hyperbolic raving, leave it alone. Reasonable people will discount unusually vindictive reviews, and happy customers will likely rise to your defense.

3. Engaging in Unsportsmanlike Debate

Thought leaders sometimes engage in online sparring matches—lively, productive debates that end with no hard feelings. Sometimes, though, those conversations take an unfortunate, ad hominem turn. And whether an argument plays out on blogs, Facebook, or Twitter, remember this: You're fighting in public, and your reputation takes a hit every time you hit below the belt.

4. Expressing Controversial Opinions

With heavy interactivity among three major social networks—Facebook, Twitter, and LinkedIn—people can easily blur the line between their personal and professional lives. Someone who knows you in one realm can easily find you in another. And that's why you should exercise caution when expressing potentially controversial views. For instance, is that stridently partisan political statement made via your Facebook account worth the loss of business from a professional contact at LinkedIn?