Getting your clients or prospects on the same page as you, by demonstrating your understanding of their pain, and then suggesting that you have a remedy to that pain is one of the keys to successfully changing them from prospect to customer.
Both points Seth is good enough to mention in hist blog. But I would add that we cannot forget to include the ever important W.I.F.M. (what's in-in for ME) and the desire to feel that it was their idea.
Get them on board with the problem, present them with a beneficial alternative, that makes the individual succeed as well as the company and let them THINK it was their idea.