In sales there is a tendency for people to want to over talk and feature dump everything they perceive as great attributes about their product or service. This is exactly the wrong approach and one of the main reasons people try to avoid sales people like the plague. The right balance is speaking about 20%-30% of the time, and responding and helping the remaining amount of time.
A good sales person asks thought provoking questions that elicit answers from customers that tell a story and really explain their needs. Good questions set you up to hear insightful details about the true desires of your prospect, but you must be listening closely to pick up on them. Good questions are open ended. These typically start with how, what, why, when, where. When the prospect is talking, don't think about your next sentence. Only listen to their words, the inflection they use when speaking and watch their body language. Doing this will provide everything you need to understand the prospect. When it is your time to speak, piggy back your statements and solutions using the same words that your prospect did.