There’s only one rule about branches: anything in the master branch is always deployable.
Instead of working in master, changes should be merged in via Pull Requests from other feature branches or from a fork.
To this end, you should protect the master branch to encourage code reviews before changes are merged and deployed. This will prevent work from being performed directly on master, and will foster collaboration among CoA developers.
masterSome developers have (rightly) expressed concern about this review process potentially delaying critical fixes from going in in response to a fire drill. Fret not! Owners of the repository and the Organization it lives in can always force the merge even if the PR hasn’t been reviewed by a 3rd-party.