Get a college education. This is an essential first step to be considered in the publishing industry. Popular majors include Literature, Marketing, or more targeted publishing courses.
Do an internship. This is actually one of the most essential and most difficult steps, because it will get you in the door of a company, but they are some of the most competitive positions available.
Start at an entry-level position, such as an assistant, and start on the promotional track. Publishing is competitive, and it is good to start small and get your feet wet before plunging in.
Develop a keen eye. Excellent publishers and editors have well-honed instincts. Learn to develop and trust yours by absorbing all you can.
Network. Publishing is a much smaller world than you think. Develop a list of contacts, and stay in friendly communication with them, because it will matter. Who you know is as much a battle as what you're capable of, so learn to talk to people and network.