One of the advantages of publishing with a royalty-paying house is not only that you get your book inside the stores, but media hosts are more likely to interview you. Many hosts have a policy against interviewing authors of self-published books. That's a reality, and even though they might make concessions, don't count on it.
If you self-publish, the total burden for marketing is your responsibility. That's why few authors make it big on their own. It's a lot of work and almost a full-time job.
If you're with a traditional house, their promoting your book will be limited in time (possibly three months) and certainly in scope and money. Remind yourself: Whatever they do is never enough. You need to work with publishers, and then do what they don't do, won't do, or say they can't do.
And radio interviews are an easy first step for newly published writers.
If you can afford it, hire a publicist. Their rates vary from about $500 a month upward to $3,000 a month—and some may be even more expensive. They usually contract with you for three to six months. Rarely do they go longer. By then, they have contacted all their resources.
If you can't hire a publicist, you'll have to figure out how to get your press kit to the channels and stations for interviews. (My next blog entry is about press kits.)