Check out "Perl Best Practices" by Damien Conway, and the more recent "Modern Perl" by Chromatic. Both can be had as paperbacks, and I think both are also available free on online.
I'll go further. Ignore the Perl specific bits and Conway's "Perl Best Practices" is one of the best general programming books ever written.
It has so many great pieces of advice that apply to any programming task, everything from naming variables, to testing, error handling, code organization, documentation, etc, etc. Ultimately, for timeless advice on programming as a profession the language is immaterial.
With a team where everybody wrote it in a similar style, Perl did perfectly well. Mod_perl was fast. I liked Perl.
Then Django came out, and then Numpy, and Perl lost. But Python is still so incredibly slow....