Tone of Voice: Imitate How Your Members Interact
Look at a few dozen recent posts to the community. What tone of voice are they written in?
Are they laced with sarcasm and good humour? Are they direct and confrontational? Are they helpful and compassionate? Are they formal and well-reasoned?
Your tone of voice, especially when creating content, should match the community's. You're reactive here. You study and imitate. You understand what the tone of voice is and embrace that tone of voice in the community.
Too many communities embrace a rigidly polite customer service of voice. This is fine for customer service, but it's terrible to give a community its own sense of identity. Members want to feel this is a place for them. The content on the platform has to show that this is a place for them, you're building a group identity.
Naturally, oganizations will hate this. They will have strict guidelines. Be compassionate and helpful. Don't be rude. Never swear. These rules might work great in one to one interactions. But they're ill suited to developing a sense of community amongst members.