Society of American Archivists: https://www2.archivists.org/groups/museum-archives-section/standards-best-practices-resource-guide
Museum of Obsolete Media (obsoletemedia.org): This is a fascinating resource for understanding the types of media that have existed over the years, some of which you may or may not run into when archiving
US National Archives: https://www.archives.gov
Archives Gig (archivesgig.com): Fantastic resource for finding open archive gigs.