The movie has something for everyone, a comedy tonight, but I'm actually talking about:
Blogging is sometimes very different from "social networking", and one of the key things is that there are no private conversations. On the technical side, that's basically impossible: A blog post is public, or it wouldn't show up in feed readers, search engines, or micro.blog. And even "private" messaging in Twitter or Facebook is stored in plaintext on the server, where the staff can read it for laughs or social engineering or selling you to advertisers and Russians.
In the socially stunted worlds of Twitter or Facebook, often someone posts, and the first person to respond may feel like they "own" the conversation, anyone else responding is a "rando", and the lack of proper threading makes conversation very difficult so they just hate everyone. There is, I fear, not much that can be done for many of these; they grew up feral in an innately hostile environment, and won't or can't read about how to have longer discussions. Robert's Rules of Order this is not.
Blogging is about people contributing to a public dialogue. As we had in web forums, or USENET, or college dorm halls, or actual forums going back to Rome and ancient Greece. Threading and arguments about ideas are not just OK, but encouraged, just don't hit below the belt.
You may be able to learn from USENET netiquette (somewhat old link, but anything quoting Eugene Spafford is good).
When being sarcastic, if there's any danger of misinterpretation, use a smiley. Excessive sarcasm is often counter-productive and hurts people's feelings, even when it's unintentional.
—a rule I sure don't live by