Were you one of those people who used to put up folders or books around your desk in school so other students wouldn't look at your test? You remember how it worked: you would build a little fort around your desk to prevent unprepared eyes from wandering over to your answer sheet. In school that probably wasn't a bad idea, but when it comes to social media you don't want that mindset at all. In fact, you want people to steal your ideas. If people steal your ideas and your content that means you have ideas worth stealing...and that's a great thing.
Thou Shalt Create Good Content First
Now, I know this sounds strange and counterintuitive because, after all, who wants to be a victim of content thievery? The reality is that in the world of social media, all you really have are your ideas and content...or to be more exact, content that communicates particular ideas. In order to benefit from that content you need people to find value in it. Good content has value to the reader/viewer/listener so when you create good content you're making yourself more valuable only because you're providing value to someone else. This is the heartbeat of social media marketing.
Thou Shalt Not Worry If Content Is Stolen
If your content is stolen it did just want you wanted it to do. It resonated with someone because they found it valuable (probably in one of these five ways). Ideally, you'll get credit when someone steals your idea/content. It would be better for everyone if they provide the appropriate link or credit to you so you get the attribution, but even if they don't you ultimately accomplished what you wanted. If you don't get that link from the person now, you may get it in the future.
More than likely it was an oversight on the person's part and not a malicious or intentional misrepresentation. Besides, Google has a funny way of bringing things together, so if a blogger takes your content as his own, a mere Google search on the ideas will likely lead people to your blog. If that's not enough for you, just send an email to the person thanking them for passing your ideas along and ask that they link to you in the future. Don't accuse them of anything. Just be gracious and kind. They'll likely fix the post and be more mindful in the future.