What are some good rules to follow when handling people who want to collaborate on a project that is on your personal repo?

It looks like GitHub doesn't allow fine control of permissions unless it is an organization repo. I looked around and a lot of other projects (specifically browser extensions) still live on the main dev's account. I don't have any reason to doubt the people who want to help, but it might be nice to know what the best practices are.

Should I add everyone as a collaborator? This runs into the issue above where I can't limit permissions.

Should everyone push contributions from their forks? In that case, how would people work together on a particular feature.