There's a big but, though. It's important to keep in mind that there are some lines that shouldn't be crossed on social media. For one thing, a steady stream of nothing but self promotion often comes off as desperate. It's better to have real conversations and share content from others far more than you promote your own work.
This week, VOYA magazine (a journal of YA literature) provided a stunningly terrible example of something else to avoid on social media. There's a more extensive summary of the whole garbage fire here on SorryWatch, but the general gist of it is that VOYA published a review with an offensive line in it. When the issue was (politely) pointed out, the person handling VOYA's social media responded with an escalating series of defensive, angry posts. Instead of handling the situation quickly and responsibly, they drew more and more attention to themselves and their mistake.
It's generally not hard to avoid offensive speech or language on social media, but there's always the chance that you might inadvertently upset a person or group. If this happens, the correct thing to do is always to apologize—immediately and sincerely. Listen to what people tell you. Learn from your mistakes.
While it's completely acceptable (and encouraged!) to be yourself and express your opinions on Twitter, Facebook, Tumblr, and the like, make sure it's your best self you're putting forward.