It's also fairly common to have a hybrid between scripts and modules. You can create .t files for individual sets of tests, but place common functionality into a .pm file within the t/ directory that each of your .t files uses. As an extensive example of how this might work, see Test::Class -- though it's perfectly fine to just create a simple module with some helper functions, too, so you don't repeat them in your test scripts.

Personally, I think using Module::Starter to create your test module is overkill, as most of Module::Starter is oriented to creating a framework for packaging up modules for distribution which you don't really need.