Just leaving the copyright symbol is enough. I know there are also a couple of services that regularly check if someone is copying your stuff but I think those are paid,I'm not really sure. I know hubpages has a service that does this so I'm sure there are others that cater to bloggers.

The best way is to just make sure that google indexes your stuff quickly though. So regular writing, social bookmarks, ethical linkbuilding, and social media. Basically you just have to be the firs to have the content indexed. that way google will consider you the main source and everything else as just duplicates.