My profession affords me the opportunity to work and talk with many entrepreneurs and other leaders about social media. Just as important, I observe their use (or nonuse) of social media.

Twitter remains one of the most popular platforms for people to exchange ideas, promote news and express opinions. I'm a social media enthusiast, but my work in employment law makes me all too aware of the risks inherent in these instant-post tools.

My Top 10 list of costliest mistakes might surprise you. Its entries stem as much from underuse as from misuse.

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