In addition to advertising your books, sometimes you have to advertise yourself. That might sound terrifying to an introvert--which I've read most of us authors are. But, it does appear to be true that readers want to know more about the authors of books.
Places to be interviewed abound online. Bloggers often are begging for authors to answer a battery a questions by email. Podcasters are often calling for interviewees as well. There are also shady types that will ask for money to interview you. Don't fall for that. You wouldn't pay a reader to buy your book, so don't pay to get interviewed. There are plenty of folks that will talk with you for nothing, and thank you for participating.
Interviews act as ads--readers/listeners may check out your catalog. If you gave a good interview, said something they liked, they may buy something. An even more effective use of the interview is to offer a giveaway to listeners/readers of the interview. Schedule a Kindle Select day, or offer to give away some stories or books to the first X number of responses you get. Some podcasts like to give away prizes--pony up a few print copies of your book.
If you do decide to do an interview, there are several things to keep in mind:
1. Know the audience that will be reading/listening to your interview. Check out that blog or podcast and see what kind of things it covers. If a Christian blog wants to know about your latest epic adventure, don't ramble on about the occult. If a scifi blog is hosting you, try and avoid cracks about Trekkies. The point is, say stuff that will go over good.
2. In the same vein, think before you speak or write your answer. Unlike your ebook, you can't take this back and republish a better answer later. Once it's out there, it's out there. Proof your answers if it's a written interview--apparently a lot of bloggers don't do that. If a prospective reader sees you spell like a third grader, they might not want to give your books a shot.
3. Don't be short and sweet. Long-winded might be okay as long as you're not bullshitting. Brief answers don't really serve any purpose, despite how badly we introverts want to give them. People are reading/listening because they want to know more. So let them know! Also consider that if you're doing a podcast, your interviewer may not be that good at it. They may expect you to be supplying all the talking and thinking. Heck, they might not even have questions prepared. Podcasters do wing it sometimes, so be prepared to fly!
4. Have a good picture of you and your product. Whether it's a blog or podcast, you're going to be asked for an author picture. You don't have to run down to the latest studio and drop several hundred dimes for one, nor do you have to spend days agonizing over the perfect photo. Just have someone take something representative of you. If you do live appearances (conventions, signings, etc) people will see you as you really are. They aren't looking to judge you, they are looking to judge whether you can write. So just come across as competent and knowledgeable about your product. And don't be overly weird.
If you can't find a place to give an interview, ask for them. Blogs are cheap and easy to start. Start soliciting other authors to do interviews, and maybe someone will interview you.
If that doesn't work... well, interviews are just part of the advertising process. Don't sweat it, if it isn't you bag.