All the great sales tools and knowledge out there won't do you any good unless you speak the language of your audience.
You can be the slickest talker in the world and you won't get anywhere with someone that thinks salespeople are walking gimmicks. You can be the best listener in the world and you won't get anywhere with someone who has trouble expressing what they really want. What you need to be is a great processor. You need to know how to ask great questions, read body language, and hear the unspoken communication; then you need to internalize it, interpret it, and translate your message into something that will hum on their emotional and intellectual level. That's what makes a great salesperson; that's how to professionally help people buy. Not a talker; not a listener ... a processor.