Ultimately the quality of the food you serve will draw people to your service window; however customers are far more likely to return for purchases of your menu items if they feel valued by the person selling it.
Under-appreciated customers will look elsewhere to make their next food purchase. Reach out to each of your customers and make sure they know how important they are to your business. Give them the opportunity to meet as many of your staff as possible. Have your service window staff thank them for their business and ask them to tell them a little bit about themselves. When you or your staff creates an emotional connection with your customers, they are more open to hearing what you have to offer, and much more inclined to keep coming back for more. This interaction needs to be genuine and shouldn’t never be phony or insincere.