Add a Changelog (best named 'Changes') to the distribution. It should list at least major changes implemented in newer versions.
Add =head1 LICENSE and the text of the license to the main module in your code.
Add a META.yml to the distribution. Your buildtool should be able to autogenerate it.
Run a proper command ("make manifest" or "./Build manifest", maybe with a force option), or use a distribution builder to generate the MANIFEST. Or update MANIFEST manually.
Fix the version(s).
List all used modules in META.yml requires
Add =head1 LICENSE and/or the proper text of the well-known license to the main module in your code.
Add a META.json to the distribution. Your buildtool should be able to autogenerate it.
Add tests or move tests.pl to the t/ directory!
Define the license if you are using in Build.PL. If you are using MakeMaker (Makefile.PL) you should upgrade to ExtUtils::MakeMaker version 6.31.