Tease out tasks in your issue tracker to help others understand where they can get involved and what's being worked on. Issues communicate specific needs or questions to contributors. Take time to document tasks, features, bugs, or questions in the issue tracker to let others know how they can help. This is often the main forum for public discussion on a project.
Jumping into a new project can be hard and intimidating. Lower the friction to join in by having contributor guidelines (usually in a CONTRIBUTING.md file, linked from the README). This document will help others understand the way your community works and how you interact with each other.
Good questions to address in contributor guidelines: