How do you get your potential clients to open up to you about what they need?

1. Be honest from the start
2. Respect
3. Don't judge
4. Listen cafefully
5. When a potential client offers objections, uncover the truth behind them.
6. Give your honest opinion after hearing the needs of customers

By outlining that the real value lies behind the alignment of the subject product(s)/services(s) with achieving thier strategic goals. Objective presentation of success and otherwise examples might help in this regard.

It's important to know about the clients organisation, their business, their credit rating before probing to understand their needs. Clients background information helps the sales person to put the right probing question and also facilitates the client to understand their needs.

Probing could be with close ended questions or open ended questions depending upon the kind of potential client being faced.

A small need expressed by the client may be converted into a big need if background information were available. 

make realities between your customers on his likes and dislikes,,, this will creat a soft communication between him and you,,, he will tell you how and when he will really use your product.