Some fundamental questions are the very foundation.
In my line of business, most people nowadays buy a split air-conditioner and a few others buy a window air-conditioner.
The very first question I normally ask a customer is: Are you looking for a window air-conditioner or a split air-conditioner?
Last month a customer asked us to inspect his window air-conditioner. Our technician reported back saying that it would be wise to replace the unit. We spoke to him and told him that it would be better to replace his unit. He referred the matter to his friend who is known to us since long.
Later this friend phoned us and asked us to send the new air-conditioner. We sent the new unit forthwith. When the unit reached the customer's place, he phoned up and said " But I wanted a split air-conditioner."
We had to bring back the unit and had spent considerable time and money which could have been avoided.
We re-learnt that an ounce of prevention is worth a pound of cure.