in reply to
Is a book like Advanced Perl Programming the answer?
Others have given good suggestions for other answers (And I second merlyn's recommendation of Effective Perl Programming. I just got a copy and it's full of the little subtle tricks that you
can normally only gain through experience).
What I can add is that I don't recommend Advanced Perl Programming for topics such as GUI's, signals, or sockets.
I've just finished my first sockets based program, and APP didn't help beyond learning to use the IO::Socket and IO::Select commands.
I used to recommend APP for learning Objects and Modules, but now the perlboot, perlobj and other pages are actually better
documentation for it. APP skims the surface of the advanced topics you're looking at too lightly.