"Make a customer not a sale" is a quote coming from Katherine Barchetti, upscale retail queen of the 70s and 80s. The K. Barchetti shops were New York style in Pittsburgh. A newspaper article described her as "In her heyday, Katherine Barchetti was Pittsburgh's retail success story, a platinum blond grandmother who outsold, outpriced and out dazzled the competition."
It refers to treating the customer as a person with whom the company wishes to cultivate long-term relationships, to build rapport, not as a mere statistical number, usually the result of pushing a sale. According to this expression, the customer is a long-term investment, not a short-term opportunity.
We always try to be honest with them and not attempt to reach the sale (e.g. we don't need to sell them the most expensive product or perhaps something they don't need) and we make sure that we create realistic expectations (e.g. realistic description of our hotel, without the use of misleading photos).
We show that we care and that our focus is always on the customer and their needs, always offering them quality products and services - sometimes preventing them from buying something that may not adequately meet their needs.
To make a long story short: treat your customers right, respect them, listen to them, treat them like a V.I.P., buld trust, follow-up, thank them.
Some time ago, a very good friend and business associate ordered pizza. Although she had been informed for the long waiting time, around 50 minutes, at some point the phone rang: "."...due to an error in your order we have been delayed an extra 10 minutes, so we would like to inform you that your pizza will arrive in five minutes and it will be on us...".
They just won a lifetime customer - maybe many more, since we live in the age of social media.