Use exceptions instead of calling croak()
This little bit of test code was causing me a lot of grief:
You see the regex for qr/Table.1111111111.doesn't exist/? Due to a slight rewording in the error message, that test kept failing. However, it was failing in a way that the following test used to keep failing. As it turns out, I had fixed a bug these tests were designed to catch but it looked at first like I hadn't fixed the bug. Because of the changed error message (and me misreading the test number), I spent a lot of time trying to track down a bug that did not exist.
If I had been throwing proper exceptions, my tests would be trying to validate the class of the exception, rather than the text of the exception. I could have changed my error messages at will without worrying about breaking my tests. Yet another reason why you usually want exceptions instead of calling die or croak.
Exceptions are awesome, though lacking in perl, and I'm not a fan of Exception::Class, so I wrote Exception::Simple, it's only small and basic, but allows you to do what you state here. I've never looked back since, I throw Exceptions left, right and centre these days!