use open questions to gather information - typically for example, questions beginning with Who? What? Why? Where? When? and How?
when training or learning the skills of using open questions it helps to refer to the Rudyard Kipling rhyme: "I keep six honest serving men, They taught me all I knew; Their names are What and Why and When, And How and Where and Who.." This is from Just So Stories, 1902, The Elephant's Child - see other useful and amusing training quotes and maxims.)
use "Can you tell me about how..." if you are questioning a senior-level contact - generally the more senior the contact, the bigger the open questions you can ask, and the more the other person will be comfortable and able to give you the information you need in a big explanation
'what...? and 'how...?' are the best words to use in open questions because they provoke thinking and responses about facts and feelings in a non-threatening way
use 'why?' to find out reasons and motives beneath the initial answers given, but be very careful and sparing in using 'why' because the word 'why?' is threatening to many people - it causes the other person to feel they have to defend or justify themselves, and as such will not bring out the true situation and feelings, especially in early discussions with people when trust and rapport is at a low level
listen carefully and empathically, maintain good eye-contact, understand, and show that you understand - especially understand what is meant and felt, not just what is said, particularly when you probe motives and personal aspects
interpret and reflect back and confirm you have understood what is being explained, and if relevant the feelings behind it
use closed questions to qualify and confirm your interpretation - a closed question is one that can be answered with a yes or no, eg., "Do you mean that when this type of equipment goes down then all production ceases?", or "Are you saying that if a new contract is not put in place by end-March then the existing one automatically renews for another year?"
when you've asked a question, you must then be quiet - do not interrupt - allow the other person time and freedom to answer
the other person (your 'prospect' in selling language) should be doing 80-99% of the talking during this stage of the sales discussion; if you are talking for a third or half of the time you are not asking the right sort of questions
do not jump onto an opportunity and start explaining how you can solve the problem until you have asked all your questions and gathered all the information you need (in any event you should never be seen to 'jump' onto any issue)
all the time try to find out the strategic issues affected or implicated by the product/service in question - these are where the ultimate decision-making and buying motives lie
if during the questioning you think of a new important question to ask note it down or you'll probably forget it
when you have all the information you need, acknowledge the fact and say thanks, then take a few moments to think about, discuss and summarise the key issues/requirements/priorities from your prospect's organizational (and personal if applicable) perspective
questioning is traditionally treated by conventional sales people and conventional sales training as a process to gather information to assist the sales person's process, and this is how it is typically positioned in the old-style 'Seven Steps of the Sale'; however, modern sales methodology treats questioning in a radically different way - as an essential part of a facilitative process whose purpose is to help the buyer decide (see the information about collaborative selling and buying facilitation for more explanation)
questioning is a fundamentally important part of selling - techniques being increasingly developed and refined far beyond early selling techniques - transferable to and from other disciplines (notably coaching, counselling, therapy, etc)
see for example Sharon Drew Morgen's excellent facilitative questioning methodology and the Clean Language concept