People records must be matched correctly.
See Mismatched People Records
The number of Contacts marked as Duplicates should be kept to a minimum.
See Duplicate Contacts
The number of records using Default Contact should be kept to a minimum.
See Default Contacts
The number of Contacts with an Active status should reflect the people who are actually active in your church.
See Active vs. Activity
Contacts should have a Household.
See Contact No Household