Getting people to buy

85% of the U.S. population uses social media which means  if any self-published author wants to sell their books, they should start  using social media. Sometimes I wish I'd taken marketing at university instead of plain old English Lang & Lit but then marketing was barely heard term at the time. Already I can hear my d-i-l telling me "Marketing is not selling, Jen."

She has tried many times to explain the difference to me, since her field is - you guessed it - marketing. 

A normal dictionary definition of marketing is: 

"the action or business of promoting and selling products or services, including market research and advertising."
However, the business online dictionary goes further:

"The managementprocess through which goods and services move from concept to the customer. It includes the coordination of four elements called the 4 P's of marketing:
(1) identification, selection and development of a product,
(2) determination of its price,
(3) selection of a distribution channel to reach the customer's place, and
(4) development and implementation of a promotional strategy.
For example, new Apple products are developed to include improved applications and systems, are set at different prices depending on how much capability the customer desires, and are sold in places where other Apple products are sold." 

Read more: http://www.businessdictionary.com/definition/marketing.html#ixzz48cWB0Yg9
So now you see why I wish I'd done this at uni. How on earth do I go about discovering peoples' habits, hobbies, interests? Help!