'Social media' and 'marketing' - for great business in 2016, they definitely go together. But it's possible to be great at social media without being great at marketing. And great at marketing without having a clue about social media. Social media can grab attention, but is it the right kind of attention? Does it build trust? Does it keep people engaged? Does it boost your traffic, bring you leads and close the deal? Here are four principles for getting it right.