Remember their name:
Three experiments demonstrate that remembering someone’s name facilitates their compliance with a purchase request made by the rememberer. Experiment 1 shows that name remembrance increases request compliance, but name forgetting does not cause a decrease in compliance. Experiments 2 and 3 show that name remembrance is perceived as a compliment by the person remembered, which mediates compliance with the purchase request. Experimental manipulations of the likelihood of name remembrance (experiment 2) and need for self-enhancement (experiment 3) provide results consistent with a complimentary explanation for the findings.
Source: What’s in a Name? A Complimentary Means of Persuasion” from Journal of Consumer Research