projects should not just say that they welcome new members: they should make a proactive effort to foster positive feelings in them. One way to do this is to post a welcome message on the project’s social media pages, Slack channels, forums, or email lists. Projects might also consider maintaining a dedicated "Welcome" channel or list, where a project lead or community manager writes a short post asking newcomers to introduce themselves.

I have not found it especially helpful to have a place set aside for the express purpose of letting newcomers introduce themselves and be officially welcomed to the community. This is an extremely shallow way to do this and I don't believe it's especially effective.

(I am not an open source maintainer. I do have moderating experience.)

It's generally better to "greet people at the door." In other words, the first time a new person says something, engage them. Be polite. Be respectful. Try to keep things on topic.

If they ask a question and it doesn't get a reply within X period of time, reply to it even if you don't know the answer. Don't make them feel ignored. Replying may bump it and get it answered. Even if it doesn't, they won't be afraid to keep talking.

"The silent treatment" should be used to intentionally starve problem behavior of attention (a la Don't feed the trolls). It shouldn't be seen as a valid response to a newcomer just because you don't know what say to them.

Keep knowledge up to date and findable

You can't document everything and newcomers don't necessarily read your extensive documentation.

I would focus on making sure some key stuff is covered and occasionally reread it to make sure it doesn't say anything egregiously wrong and misleading because things have changed. Minimal, accurate documentation is more useful than extensive inaccurate documentation.

They recommend that you have and enforce a code of conduct, then admit Research on these is still in its infancy.

If you are in an influential position, get with the person in the mirror regularly. If you see a problem behavior cropping up regularly, wonder what you are doing that is inadvertently causing that to somehow be acceptable and make sense to people.

Watch your sense of humor. It is often a source of unintended consequences.

Codes of Conduct, like Rules of Law, basically are their most useful when something has gone very, very wrong and a third party needs to arbitrate. They mostly aren't that useful for fostering good behavior. You mostly foster good behavior by how you comport yourself.

Too much focus on Codes of Conduct can be counterproductive and can signal "We are so badly behaved, we need it constantly explained to us what good behavior is supposed to look like."

It's good to have some guidelines and best practices, but be careful that you don't spend an excess of time overly focused on nominally rooting out some particular evil.

Think of it this way:

If you feel you need to state up front in your dating profile "No Rapists!!!!" then maybe that dating site should be skipped altogether. It's fine to do a little polite hand slapping occasionally to establish where to more clearly draw that line, but you shouldn't need to aggressively focus on things that should "go without saying."

Ironically, a genuinely healthy and well mannered environment has a certain tolerance for interpersonal friction. It needs to be a place where hand slapping can occur without turning into major drama.

An environment where everyone needs to walk on eggshells is not a polite environment. It's a terrifying and very unhealthy environment.