A well-developed README that promotes the project. Screenshots, explanations, an FAQ, release notes, info for collaborators, links to download or test. Basical

A well-developed README that promotes the project. Screenshots, explanations, an FAQ, release notes, info for collaborators, links to download or test. Basically, the github repo as a homepage for a product rather than just a dump of text files. This shows that your thing is a finished project or under ongoing development rather than just a dump of some source code that you once wrote. It's the equivalent of having an app on the app store vs. having a half-baked Xcode project on a computer.