" Many hospitality companies follow the "5 and 10 Rule," whereby when a customer is within ten feet of the employee, they should provide acknowledgement with eye contact and a genuine smile. When the customer is within five feet, it is encouraged to provide a warm welcome, sincere greeting, a friendly gesture, and offer to help, or to engage him or her in conversation. "

― Susan C. Young , The Art of Body Language: 8 Ways to Optimize Non-Verbal Communication for Positive Impact (The Art of First Impressions for Positive Impact, #3)