I am always refining my Best Practices and keeping up-to-date on Security Measures.
There is more to installing a plug-in or a theme and configuring it than the work that you can see. There is security to be dealt with behind the scenes. Everything from keeping your passwords safe to being certain that your permissions are set to a secure level on your server.
I believe my professional approach in all areas, but especially in this area, sets me apart from rogue freelancers you might find on some bulletin board somewhere.
For reference, here is a link to the section on security at WordPress.org: Hardening WordPress