All good suggestions so far, but I haven't seen any discussion about test suites. Ideally your code is separated into modules, each one with a decent set of tests, both unit tests (tests for modules as standalone units) and integration tests (tests for the modules working together).
It's also a good thing if perlcritic is reasonably happy with your code base.
If you have a way to stage your code in such a way that it's as close to the production environment as possible, great -- that'll give you an opportunity to road-test your code (after all the tests pass and code review).
Probably the most important thing has already been mentioned -- get your code into a VCS, and make sure you have a really good handle on exactly what version is currently running in production.
Alex / talexb / Toronto
Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.