Selling more requires a multidisciplinary and continuous method
Selling is a relationship between a buyer and a seller, that is, between human beings. So, it is only logical that a deep understanding of how people think and communicate their view of the world is essential to be able to sell successfully.
The starting principles begin with those of persuasion, but it certainly does not end there: selling is a process which brings together the key components from several different disciplines to provide the seller with a set of winning tools he or she can use to ensure success.
The most important part of the process that leads to making a purchase takes place in the buyer's mind, just below the level of conscious thought. This involves looking at the science of the unconscious, hypnosis, neuro linguistic programming, and neuroscience to literally transform the way you sell.
There is only one caveat: you don't learn everything at once, but you do need to apply a "growth plan" to your sales skills, as you gradually learn to take advantage of every new tool that is made available to you.