The basic differences between good church publications and inferior ones are good design and a consistent editorial voice. Adopting a congregational style guide is an achievable way for churches to improve the way they present themselves to others, and unlike other improvement efforts doesn’t demand a cash outlay. A common, public standard might soften hurt feelings about that awkwardly-written contributed article that had to be changed.
While the parallel is imperfect, the style guide for Wikinews is as close as any I have seen for adoption by a church newsletter, and most of it — the parts written after September 25, 2005 — is available under the Creative Commons 2.5 Attribution License, which is about as free as they come. It would allow, for instance, for a church or other entity to use the style guide — and with attribution — adopt it for their own use and pass the product along for others to use.
Do you know of any other style guides that can be shared?