First of all the Cookbook is not just for amateurs and
quick hacks. I find it to be a very valuable resource.
As for good software development, most of that is not very
specific to any language. The fundamentals of programming
well don't change just because you are programming in Perl
now. However among the classics on that topic, the one
that I know of with the strongest Perl bent is probably
Pragmatic Programmer, The.
For pointers on good Perl style, well books like
Effective Perl Programming are meant to address that.
But still there are a plethora of good resources out
there. If you do not know the material in them, all of
the books that I just mentioned are probably worthwhile
to read. Not all at once, of course, but start somewhere
and start learning...