#!/usr/local/bin/perl -wThis will help you (really, it will force you) to write better, cleaner code. Adding the -w switch to the perl interpreter will cause it to spit out warnings on uninitialized variables - potential bugs. 'use strict' turns on the 'strict' pragma which will make you declare your variables with the my keyword. 'use strict' also tosses up errors if your code contains any barewords that can't be interpreted in their current context.
Start using those two lines, even if it seems like extra work. The payoff comes in the form of code that is more easily maintained. You can read more about 'use strict' in the Beginners Intro to Perl tutorial from Doug Sheppard on Perl.com
Beginners Intro to Perl - use strict