I believe in follow through. If you make the sale you follow through with that client and make sure they are happy 1 week, 1 month and even 1 year after purchase. It is your obligation to keep this client happy even if it was a one shot sale because they will tell others about their experience.
Also, if you sell a client a product that needs to be serviced make sure that the employees who service the product are as “warm and fuzzy” as you were to the client. There is no greater turn off then to be “wined and dined” and then go for service and have a less than satisfactory experience.
I write this because I had a less then memorable experience myself the other day. The sales part of it was great. I felt important like I was the only customer they had but when I went back for service I was rushed, I had to ask my questions twice before they would answer and there were no smiles anywhere to be found. When I left I felt that since they had sealed the deal I was no longer that important to them.
We cannot remember every single person but a “smile” and a “hello how are you?” can go a long way to a lasting relationship.