Main idea and context
What different types of people could contribute?
How would your project integrate a neuroimager/clinician/psychologist/computational scientist/maker/artist as collaborator? You can check the Mozilla Open Leadership material on personas and contribution guidelines.
Try to define intermediate goals (milestones).
Provide links to preparation material / online tutorials. You can, for example, have a look at our list of online tutorials.
YourGitHubRepo
with ReadMe.md containing
* Project idea and context
* Installation guidelines if applicable
* Links to further reading / tutorials
and if you want, additional files such as
* Contributors.md, to specify which types of people can contribute how.
Link to the communication channel for your project. You can, for example, create a Mattermost channel for your project inside the Brainhack community, and include a Mattermost badge 
to invite people to Brainhack Mattermost, where they can then find and join your channel.
Or create a community on gitter and link to the chat by including a Gitter badge linking to your community
