It's good to use social media to help drive traffic to your site… but it's dumb to take a screenshot of a tweet and upload it to Instagram because you thought it was funny. Likewise, if all you do is post the same thing to every social network, people will get bored and think you have no idea how social media works. What's right for Instagram isn't always going to get the same kind of love on Tumblr. If everything is important enough to end up on your main blog, you're not doing any sort of editing, you're just regurgitating everything you produce, which makes your content look redundant.
7. Blast the same content on all platforms