In a Brick an mortar or craft show setting acknowledge that potential customer with a smile and hello. Offer assistance and choices but also breathing room for decisions to be made.
If you say you will call back, DO IT. or lose customers! Case in point:
A friend of mine is looking for a car. She drove over a hundred miles to an advertised dealership, was pre-approved for financing but didn't find exactly what she needs. She was told they would see what came in this week, check their other two lots and call her. No phone call. She checked on line, found one she was interested in, called them back, left a message, and still no phone call! Today (after a week of waiting) she found another dealership in the same town, was able to chat on-line with a rep and then call to continue with the same person. They are arranging credit and looking for her match of vehicle - have three in mind at the moment and knowing her past experience -will call back or she moves on!
Communication is also key with on-line enterprises. All questions should be answered in a timely manner, if immediate response is not feasible, then at least daily. Notice should be given if this is impossible (you're away from your computer for more than a day-craft show) . If a longer service interruption happens (your computer breaks or you are on vacation) be sure to post a notice from a public computer or have a trusted friend able to respond for you. Acknowledge the receipt of an order and communicate shipping date and estimated arrival time.
Great customer service can equal happy return customers. Only one of the steps in building a successful business.