These are great tidbits for how a contributor can get the attention of a maintainer but I think these tips also inform well on how a maintainer can get more contributors.

Recently I started a new project and got 7 contributors in a week - more than I've gotten for any project ever. [1] I think its partly due to hacktoberfest but also because I realized I can't waste a contributor's time. I made issues with descriptions of exactly what should be done - where in the code they could introduce edits, and what kind of dependencies people could use to implement, etc. Though I could have done myself, I didn't have to and I also got to see some ingenuity of other people!

[1]: https://github.com/schollz/croc/graphs/contributors