Not overwriting the queryset method on MembershipDefaultAdmin
Removing commented-out fields on MembershipDefaultAdmin
Removing 'archive to approve' option in memberships

Removing this option from the membership detail page.  If a membership is archived then another membership record will via available via the profile that will allow you to change the status of a membership.

Archived memberships cannot be changed.
Reordering filters on admin membership list page
Updating start date on membership archive list on detail page

Showing renew dates on list of archived memberships before showing the join date.