Take advantage of unpublished—aka “dark”—posts on Facebook to reach a highly receptive audience of consumersFacebook knows us more intimately than many of our friends. The social media site that made posting cat photos to the Internet feel normal has been gathering reams of data (we’re talking big data) on us from day one. Lately, the social network’s keen insights into consumer behavior have resulted in the creation of highly effective in-house advertising tools. In fact, “Facebook has probably the most ­targeted marketing tools out there today,” says Ben Smithee, chief strategy officer at New York City–based ­Relevents and founder of consulting firm Smithee Group. “Because it knows us contextually, which is so powerful. Context is everything in marketing.” Smithee says too many small businesses fail to take full advantage of the platform’s robust, ever-e