Preferably a gitter or slack chat room, where users can talk to each other and get involved. It would also help maintainers get feedback from other developers who are using this.
The README should have a badge that would point to this room.
A dedicated URL where the release bundles are present, typically something like this.
We can have a separate setup with CI, where building the protected master branch would push to this URL (or some Amazon S3 static hosting, or maven central) on successful build and all tests pass.
Creating labels and milestones on GitHub helps coordinating on the issues. Especially, in grouping them and prioritizing them. Same goes for pull requests.