My only expertise is in the mistakes one makes along the path to righteousness :S
If I could send myself of two years ago one message it would be use Modules;
. I resisted this for ages, which was mad. (A) The effort of learning how to use CPAN and its contents is *tiny* compared to the effort one saves by letting the Great Ones who compose these modules do one's work for one. (B) One actually learns a lot through learning to work with good modules.
Starting out it's easy to fall into the trap of "hell, I'll write that myself, I haven't got time to figure out this CPAN business". Let me assure you, if you have this thought, it's almost certainly a mistake, even when, on mature consideration you think in *this* case it's not.
§ George Sherston