- add LICENSE file, add license block at end of readme
- add badges, like a Travis badge linking to the project on Travis. If repo has been published to package registries, add their badge too. You can use shields.io to get them all from one place
The tagline in there should always be the same as the repo description on GitHub. With tagline, try to summarize what a user can do with the repo. And most importantly: pick an emoji for your project and put it in front of the tagline.