I found this blog post on how to get involved in a project to be a good set of guidelines, and thought I would share.
I'm curious if it would help to mention things like these more explicitly in some of our contributor docs. https://rustc-dev-guide.rust-lang.org/getting-started.html touches on some briefly. One issue that I've noticed is that people sometimes don't read, or remember, or ignore guidelines (especially if there are a lot of them), so I'm uncertain if more text would be counter-productive. Also, Rust has a lot of different projects, each with their own contributor guidelines, which I think can add to the difficulty of successfully getting involved.
Maybe this could be something teams could do while implementing the 2021 Roadmap: Not only defining what a team does and what is expected from team members, but also define what is expected from contributors in a more unified way across projects.
I really like the format of this blog post. Short, emphasized headings, you'll actually read when you see a guideline like this and then short, easy to understand explanations.