To do large projects, you will have to learn how to do large projects and intimately know your development environment.

That holds true no matter what language or environment you use. I think the real problem is that for big C/C++ projects, people tend to hire C++ software developers. For big Perl projects, they tend to hire "web designers" that learned Perl along the way. And then they are astonished that their codebase is messy...

The good thing about Perl is that you can do small and simple projects without having a lot of background in software development. The even better thing is that Perl will allow you to do bigger projects and actually have fun at the same time. But it doesn't liberate you from knowing what you do.

So learning about Perl "don'ts" mostly means learning about software development "don'ts" and Perl idioms.