It isn't very sophisticated, but "use strict;" always goes into my code and catches most of my typos. I know that I should turn warnings on, but I don't for a number of stupid reasons. (I use modules that themselves cause errors, and I have avoided the 5.6.x series, so I don't have warnings.pm.)

It is pretty basic, but useful. For full details on how it works I suggest typing "perldoc strict".

Cheers,
Ben