I recently developed a summary page on Category Guidelines to help members of the Australia Project understand more about creating and maintaining categories, and avoiding category errors.
It was suggested by the Categorization Project, that the page could be helpful for other members and Projects, so have posted it here for the use of other Wikitree members.
It has some Australian references and examples, however the page is open, and can be used as is, or copied and examples changed if required, for projects to use.
Margaret Haining Project Coordinator Australia Project