Notepad? At minimum, at least install Scite. It's not wonderful, but it beats notepad in every way, and has a very small footprint.

Next, buy a copy of Perl Testing: A Developer's Notebook, and learn about writing test suites. It's easy to get started with, and probably one of the most valuable skills a web developer could acquire.

Other sources of information (just for starters): Test::More, and CGI::Test.

Other friends: perl -c to compile but not run. usediagnostics, use warnings, use strict, set your server error logs to tail into a separate window while you're debugging on a test sever, and do set up a test server on a different port that isn't world-accessible.