Work in advertising!
The marketing industry divides itself up into a number of businesses. Some are “boutique” agencies, but most are owned by one of the world's four major holding companies. These conglomerates pursue an aggressive M&A strategy, snapping up smaller companies all the time.
Advertising — this is the generation of ads and commercials; often blatant and obvious, sometimes more subtle. The objective is generally to trick people into buying something.
Media — media companies handle the placement of advertising; they are brokers for ad space and commercial slots in magazines, newspapers, radio, TV, billboards, taxicabs and specialty vehicles, people handing out pamphlets and samples on the street, free-standing cardboard cutouts, website banners, and so forth. They handle product placement everywhere (TV, movies, celebrities, video games, &c.), ranging from the blatant in-your-face product logo to the more subtle authorship of entire screenplays just to showcase and promote particular products.
Research — The least glamorous, but not the least lucrative, market research is about figuring out what customers think they want. This takes the form of polls and surveys (phone, mail, web, email), focus groups, and a variety of surveillance and tracking methods of which the customer may or may not be conscious (loyalty programs, social media, special discount/rewards programs tied to your credit card, web bugs and cookies, specialized URLs and SMS numbers, POS questions)
Public Relations — When you need to manipulate public perception in a more covert way, you might hire a PR firm. This can be something like for when a CEO strangles his wife and suddenly there are lots of news reports about how the company produces the cleanest-burning fuels, and what great things it does for charity. It can be spin on all kinds of political events, corporate performance, and lobbying.
Medical — Because of the greater amount of regulation in the medical sector, medical marketing is handled separately. This includes the same advertising process, but with lots of fine print and more restrictions on the claims which can be made. It includes research, but with different rules on the confidentiality of data and the ways you can experiment on people. Then it extends to services not found in other sectors, such as funneling money from pharmaceutical companies to doctors (this is called “medical education”), and acting as middlemen between pharmaceutical companies and the people who produce science shows for television.
Branding — Depending on who you talk to, branding is not just the process of shaping the public's perception of a particular company or product or service, or families thereof, but also convincing the employees of the relevant companies that the particular message being hawked is the truth. Logos are part of brand identity.
There are other sets of services, as well as variations on the above, particularly in terms of targeting certain age groups or ethnic groups, but also particular industries or sectors (movies, politics). There is direct marketing (spamming) through all the imaginable media. There is also paying people to blog about certain things without disclosing their sponsorship.