My advice would be to use the Test::Builder based options.

Start with Test::Simple and Test::More. Test::Tutorial provides an introduction to these.

After that take a look at some of the more specific testing modules like Test::Data, Test::HTML::Content, Test::Pod, Test::Warn, Test::Exception, etc.

If you want a more xUnit type of testing framework take a look at Test::Class (note: I'm biased since I wrote that one).

All of the above, and many more, are build on top of Test::Builder and all play together well. Kudos to schwern and chromatic for a great library.

In the perlmonk land you may find the following of interest:

• The Joy of Test
• Automated software testing: emulation of interfaces using Test::MockObject
• Unit Testing Generated HTML
• What goes in a test suite?
• Further adventures with testing
• Micro Mocking: using local to help test subs
• Small test harness for testing basic auth

As a bit of more general advice try switching to doing Test Driven Development. It feels odd at first but does wonders for code quality once you get used to it (IMHO anyway :-)