Perl has been my primary language since 2000. I would learn it in the context of building an application. Read chapter 1 of the Camel Book (the basics), which you can get online. Then just jump in and search the web or look in the book when you run into problems.

Note: tons of stuff has already been done for you at CPAN: http:://search.cpan.org

I've also found the Perl Cookbook and Mastering Algorithms with Perl somewhat useful. However, much of their content is now in bits and pieces on the Web, and so searching for your specific problem often is enough. If you don't know the site already, check out http://perlmonks.org/.