I think the big picture for professionalism in coding goes something like this:
in reply to clean up/professionalism
Before I launch a perl project for a client, I add a standard header to all the files, that includes it's name, a short description, a version, and basic info on the license, contact info, and an abbreviated ChangeLog of major changes to the script.
- Clear and Consistent Code Design
As for "good style", that's a sort of elusive and fuzzy thing. I enjoyed reading the The Practice of Programming which relates to that topic.
As for security, I'm sure you can find a webpage on secure perl programming to measure your work against.
Also, there's nothing like good old peer review to improve code. Perhaps there's a co-worker who would be willing to look things over?