Don't put too many of your social media strategy eggs in Twitter's basket, advises Nicole Ferraro. "Twitter's internal problems with management and revenue, and its very questionable user numbers, suggest it may be futile and possibly fatal." Facebook shares that of the 600 million users who visit its site each month, half of those come back daily. But Twitter shares little beyond that it has 175 million registered users. Business Insider research found that 56 million accounts follow zero other accounts, and 90 million Twitter accounts have zero followers. So don't be too chuffed to see your posts re-tweeted!