1. Use Webmaster Tools and their email forwarding
The first thing to do, if you haven't already done so, is to verify your site ownership with Google Webmaster Tools.
It is a very useful service, or rather a group of services. Google
Webmaster Tools provide you a lot of features. One very useful one is
email forwarding. If you enable it, Google will send you emails
informing you of any problems it found on your site, such as site
inaccessibility, malicious content, malware (virus), crawl errors, and a
large number of 404s (not found errors, or broken links). Having this
kind of information can be extremely useful, so that you can
troubleshoot and correct any errors that might harm your website's
reputation.
Many
corporate and news blogs today are using a simple script that
automatically includes credit links to the original site when someone copy content
from your Website and pastes it into an email, blog post or Facebook
for instance. To track how many times someone copied and pasted your
content, there is a Free service called 
