Seriously though, if the module has a mailing list, use that.

If the bugs are open on it's http://rt.cpan.org page, send patches there.

In all other cases send the patch directly to the author.

I don't think there is any code for communication, just be polite and good natured, and be sure to explain exactly what problem you're fixing, and how you're fixing it.

When sending patches try to follow the coding style of the author, like tabs vs. spaces, or my $self = shift vs my ($self, $param) = @_, and so on. This saves the author some time fixing it up, and the code is readable to them without any work.

Also be sure to use the project's version control system if it has one. svk and darcs have the capability to submit patches via email, and it just works. Other VCSs have their own diff formats, which can be easily applied. When in doubt, send a unified diff, and no other format.

Keep in mind that your work should be appreciated, because it counts. In fact, I think that by simply submitting you've already done your part.

If you feel that the author isn't paying attention, post the patch on your website, and remind them a bit. If the patch is not a specific case, but one that applies to everyone, especially a bug fix, then it should be applied, but do keep in mind that sometimes for reasons of bloat or feature creep your patch might be rejected. If you feel it appropriate, a fork of the project (like Catalyst / Maypole, for example) might be in order.

That's all I've got to say. Thank you for helping out!