Instead of telling them how to contribute, I'd suggest telling them your goal (to get everyone more involved in the community) and ask them to think about individual ways of contributing. Suggest CPAN, or documentation, etc.

Personally, I think it's often better to contribute patches, especially documentation patches, for projects you use and like than to force yourself to start a new project of some kind. I only have one CPAN module of my own, but I've contributed patches to mod_perl, Template Toolkit, Class::DBI, Maypole, etc. over the years. I always felt like that was more useful to the community as a whole.