I can't tell you how many times I've been interrupted during my early evening hours by the voice of a telemarketer on the telephone trying to get me to purchase their wares. Being an entrepreneur and small business owner, I can appreciate how difficult it is to sell. It is my policy to listen to their pitch and then express my desire to purchase or not. Of course most times I will never purchase as I don't like buying without doing my own research.
What I do though, is listen and learn who has the better approach to getting my attention. The vast majority are simply reading off a script, these people lose me instantly. Every once in a while, you will get the one person who is convincing in their delivery. This person has the magic of salesmanship. This person leaves me with a tip or two.
I also observe customer service when I shop. What intrigues me and what disgusts me. I find I am always aware of the sales activities all around me. One simple technique which is sage advice is to use the person's name if you can. A restaurant server makes huge points when they remember a patron's name, and uses it throughout their visit.
Watch and learn the next time you leave your office. Give the sales people you come in contact with a break, and just appreciate that they are trying to earn a living as well. Even if their delivery is bad you will learn a tip from them as well.