Northern Arizona University hosts a site on Teaching Indigenous Languages. It has information on related conferences and institutes, basics of language revitalization, a rationale for the work of language revitalization, teaching methods and other resources.
Introduction to heritage languages
Wikipedia has a heritage language page, for starters.
After reading this article, feel free to comment below.
Also, further links to good summary definitions or foundational writings on heritage languages can be linked to here by pasting the link and a description of its content as a comment to this task.