The most likely way your content will be stolen is by an autoblog - a spam site set up to automatically copy articles and re-publish them laden with ads. Most of the time they’ll advertise themselves to their victims by sending pingbacks or trackbacks to the sites they’ve scraped the articles from.
There is a site called Copyscape that claims to detect copying. I’ve seen many small blogs with a sidebar banner indicating they use it, but never heard a success story.
My suggestion is to include a small signature block in the body of your feature articles, “written by Joe Bloggs on 2014-01-01” or whatever you like, with a link to your About or Contact page. And enable pingbacks and trackbacks on the About page. That way you’ll often receive a pingback from sites that re-publish it.
You can send a DMCA or C&D notice to the web hosts of sites that copy your work. Plagiarism Today explains how.