I come from a similar background, but I tend to initialize my variables. The reason is fairly simple - most of my variables store either strings that have been matched in a $[0-9], or flags indicating whether a match has been found in processing the file. These are set with lines like $flag = 1 if /pattern/;, or tested with lines like print "something\n" if $area eq "51"; so I need the flag to be initialised to 0.

Most of my perl scripts are simple stdin or clipboard text processors for doing custom greps on source code or data migration files.