I am part of a user group that is talking about developing a package that is specific to a small group of professionals from different organizations. One suggestion has been to create a user group GitHub account - what is the best practice? Individuals forking their own accounts, or a communal account?
Everyone will need their own GitHub account, regardless.
Then the question is whether the repo for the package is owned by an individual or an Organization. Sometimes Organization ownership makes everyone feel more satisfied that the joint contributions are acknowledged. If you go the Organization route, you would then add the individuals to the Organization.
Whoever owns the repo (1 individual or the Organization) ... you'll still need to decide whether to all work directly in that repo (possibly using pull requests) or whether everyone will fork the repo in their individual accounts and propose changes via pull request. If most are fairly new to GitHub and collaboration via Git, you might choose that approach, because it's harder to really goof up your master repo. The added friction can work to your benefit.