Warn Your Readers about the Consequence of Copying
When you see alarming word by word copying, all you might land up doing is to contact them in the social media page or via email, and many times they tend to ask forgiveness. Rather than creating all these baseless drama it would be nice if you do something in your blog about making it clear that you are the original owner, thereby, warning copiers of legal action in cases of breach. You might have to declare in your blog about the need to give you author credits or at the least stress the importance of getting your permission before copying the contents.
Define a Content Usage Policy
Display a content usage policy quite visibly in your blog detailing how the contents in the blog can be used. You should tell them about specs you have in place like, to allow or not allow them to republish, or use specific snippets from your blog to use in graphics, and so on. Thus you will be making it clear to your readers about how far it is okay for readers to use the content from your blog.
For republications, you can ask them to give you a link credit, which is good for you in building your link wheel as well as not losing your credibility as the author of the content. You can restrict people from completely re-publishing. You can decide to allow them to just publish 50 or 100 words and thereafter link the readers to your site with a read more note, etcetera.
Digital Millennium Copyright Act
In cases, where you see that users have infringed your policies, you can at the best file a takedown notice to Google. If you should be able to file the takedown, your content should be in compliance with the Digital Millennium Copyright Act (DMCA) and you can file a claim to Google.
Copy Proof with Copyrightwebstamp
When you do so, you might need proof to prove that you are the first owner. Of course, the contents and the date of publishing the content will prove your ownership. It would be even better if you did create a digital proof of ownership of the work by registering your work with a third party copyright website with time stamps to help with DMCA claim to Google.
If you are not sure of who has copied your work until now, you can check for plagiarism by using tools like Copyscape! and economic. A good example to create proof of ownership is available at www.copyrightwebstamp.com.