On the development side of things, maybe the following as a Read the Docs ad could work:
We need C++ developers! Volunteer in a friendly open source community and help us build Haiku.
There is an 80 character limit for these ads, so we have to keep it short and sweet.
I have an idea to make a “reviews pack” and maybe a “press kit” to help the press and any potential reviewers. It will take some time though as I have to gather information and any promotional material that Haiku currently has.