The Art of a good PR

This article is quite old now but feels like there is some good advice in here:
https://blog.github.com/2015-01-21-how-to-write-the-perfect-pull-request/

In my experience, pull requests can serve multiple purposes. The principal use is a peer review before merge but I think you can use them as points of conversation or discussion also and I don't think this is done often enough.

Also I think it is really important to convey respect and be nice.