Writing Copy That Converts Into Dollars

We've all heard the saying that people buy based on emotional impulses. I tested it myself as an outside sales rep selling office supplies which is not really the most interesting thing to pitch. Anyhow, there were customers who I caught in a good mood that day and placed an order on the spot. Then there were the customers that I had developed a "story" with.
What do I mean by "story"? Well, simply put, it is an emotional connection. It could be an experience that a customer relates to puts them in a certain mood. Empathy can usually get a good sale. For example, one of my first sales was at a pharmacy. I mentioned it was my first week on the job and the owner said they had just opened up this month. Being in similar circumstances helped me relate to him and build a small "story". We were both fairly new to our respective positions and were more than willing to help each other out.
Human psychology is a subject that's often overlooked. However, an adequate understanding is important if you want to have any success with sales or even with building relationships. As different as we would like to think we are, we usually act in accordance with the majority.
What are some noticeable buying tendencies customers exhibit?
Customers tend to value the price of an item as being definitive of its quality. They look at the price and judge how good it is depending on how expensive it is. The reasoning behind it is that if it cost more, it must cost more to make and thus have higher quality parts.
Americans are extravagant. People like to wear expensive clothes, drive expensive cars, and live luxuriously. There's a negative sting associated with anything being considered as "cheap". People would rather you say that it is a more economical alternative rather than "cheap". Therefore, a product/service must make the customer feel as if they are receiving something luxurious.
Customers would give a specific detail about your product more weight than if you said something extreme and vague like "best product on the market". Instead, try to be more specific and explain why the product is the best. Does it save 30% more energy than its competitor? Does your service guarantee at least 30% earnings increase? Include that in the advertisement and remember to be as specific as possible because people will give you the benefit of the doubt that you have done your research. Not only do you come off as more credible, but your customers have some facts that they can justify their purchasing decision with.
Tastes between customers differ. One product my be so laughable to you but it performs well in the market. On the other hand, you might think a product is the best thing in the world and it won't sell at all. In advertising, there is a saying that you have to let the thousands decide what the millions will do. You create a small test campaign and see the reaction of a large sample size. We have to know our cost, know our sale, and from that we gather our profit and loss from the campaign. Thus, we should constantly seek for better methods of advertising if one proves to be unsuccessful.
Psychological tendencies between customers can be recognized and used in our advertising campaigns. We discover how people react to our ads and our claims and we capitalize on it. Advertising is a science and if we treat it that way, we can come up with verifiable results. In today's age, nothing is more important than a well thought out plan.