My personal favorite for teaching the "right" way to learn Perl is Elements of Programming With Perl, by Andrew L. Johnson. I already knew a little bit of Perl when I bought this book, but it taught me a lot more. It also seeks to teach Perl in the context of the classical computer science stuff, so you learn less about scripting, and more about algorithms and development. This book discusses the importance of warnings and strict.

Mind you, Learning Perl will teach you a right way, too. Namely, the one where you get stuff done really quickly. You just won't learn much about the big words of computer science :-)