To prevent duplicate customer contact information, the recommended approach is to configure and activate Salesforce's built-in Duplicate Management feature. This feature allows for the creation of duplicate rules and matching rules to identify and prevent duplicates at the point of entry. It can be applied to standard objects like Contacts and can provide users with alerts or block duplicates based on the rules set. This proactive approach ensures data quality without requiring excessive manual intervention or extensive access rights like "View All Data."