I think a good example of this is the Django Software Foundation. They have a Django Fellow they employ who is responsible for helping guide the community and take care of the bug tracker and other tasks. They maintain a list of begginer friendly tasks. Release notes specifically call out first time contributors and credit them, no matter how small the first contribution may be. These callouts serve as both a thank you/welcome, and a message to the community reminding them that contributions are welcome. Every project is unique,.sounds like you guys are making a serious effort- keep up the good work!