People buy solutions to their problems. They do not buy because you are smart or nice. The absolute worst thing a salesperson can do is to try to impress the prospect with his or her knowledge. This really drives people away from you. Wanna have a few sales? Be smart, be interesting. Wanna have a lot of sales? Be interested! Being nice is nice. Mother will be pleased. Customers buy because they're in pain. They need to cover their behinds. They want to look good. They want to be respected. They will buy from you when you solve these problems; and only then.