Those people are usually art directors, producers, photo editors, agency art buyers, editors, and marketing and communication managers.
Before trying to sell yourself to any of them, it helps to do a bit of research on your buyer before sending off that promo piece highlighting your best food shots to John Doe, Photo Editor at the Women's Fashion Daily. It's important to understand as photographers, we need to be salesmen or women if you plan to stay in business in the long run. Sure, it helps if you have your own team of sales people but no one can really understand your product as well as the person who created it.
Remember, closing a sale doesn't happen by sitting in the office or house all day. It happens by being out there meeting those key people and maintaining those relationships whether they buy now or later. So go make those phone calls, take that magazine photo editor out for lunch, or get on that plane headed to China and meet those art buyers. There's a lot of content hungry people out in this world today...