WHAT IS MARKETING?
No organization can grow or likely even survive without marketing, and this is likewise true for an individual seeking out marketing jobs. Marketing makes known a firm's features and benefits and what it's going to cost someone to get them or use them, and it does the same for products, services, and those people who want a marketing career.
First things first: marketing and selling are two entirely different things. Yes, they overlap, but marketing is larger in scope than sales, and marketing is far more about attracting others to contact you than it is about aggressively making first contact and then trying to convince someone as fast and firmly as possible of your take on things. You want to advertise the fact that you possess desirable traits for an employer; you don't want to talk your way into getting hired. There is a time and place to sell yourself - at the interview.