I know that I've started to do something like:

sub foo {
    local $_;

     my ($var1, $var2) = @_;

...

}
[download]

in all my personal "production-level" code. (I'm an avid user of $_.) While this can result in a slight performance hit, I change my personal code around enough that have that template just makes me feel safer about using $_.

Just a suggestion. :)