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I would say share not only your stories but others from news sites in your niche as well.  Try to become a "Top Contributor" in those groups on LinkedIn and usually your stories will get more attention and interaction.

I can help you only with twitter: https://twitter.com/search?q=""http://moz.com""&src=typd Just replace the http://moz.com with your domain. For Facebook or Linkedin I don't think you can do that, but you can find people who liked your Facebook page or who shared your Facebook posts.