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...