I’ve been there before with Gentoo, as a developer, but times and situations have changed. Over the years I’ve been deeply involved with Ubuntu for my work and at its heart, Debian. I’ve become a Debian Developer to help get closer to the development process, package management and maintenance to do my share of the heavy lifting.
The first thing I did was sign up at Alioth, a software ‘forge’ used by Debian for collaboration. Create a ‘New Account’ and just be aware that whatever login name you use, it will be appended with ‘-guest’. This will go away once you’ve officially joined Debian. At this point, it is also a good idea join a Debian mailing list and/or join IRC at irc.debian.org and have a nice chat with the folks in #Debian or their various sub-channels where you would like to help. It is important to have a sponsor/mentor that can help you out if you a problem. You will need them when getting accepted into the Debian community in order to start working.