Virtual book tours are a new-ish marketing tactic to help gain readership for your novels. On the simplest level, you're going blog to blog to promote your book. The main tactics used to market your book is the author provides guest posts, excerpts from your novel, interviews and giveaways. The blog host can share a review of your book. Each blog stop will typically do a combination of these things on the days they host your book.
Now, one option you have is to request guest posts, interviews, etc. from blogs directly. However, this could be time-consuming and you could have no idea where to start. If you know a lot of fellow bloggers though, this could definitely be a possibility. The simplest option may be to hire a book tour company. For a flat fee, you pay them to act as a middleman and set up your appearances on various blogs. They help work out your guest post topics and provide you with the blog's interview questions. They put together a press kit after you send them a copy of your book, selected excerpts, your bio, etc.
I'm scheduled for two tours using two different companies over the next couple of months. My first tour for First Visions begins May 28 and is through Reading Addiction Blog Tours. My tour will be a month long and stop at 20 different blogs. 10 of the blogs will have review stops and bloggers are asked to cross-post reviews on Goodreads, Amazon.com and Barnes and Noble. I figure this will also be a good way to get more reviews since my book has only been out for three weeks. The pricing packages for both companies started around $25 and went as high as $150. The month long blog tour package ranged from $75 to $100 and both have 20 stops on the tour.
I'll be cross-posting during the month, so check back for giveaway links and more. I'm also sponsoring a giveaway on LibraryThing for free ebook and paperback copies of First Visions. Members can enter here.