What to write about on a blog tour?

When I ask for guest posts for my blog, I usually like to see a topic related to writing or the book they are promoting. So, for example, when I had someone promoting a novel about genetic engineering, she sent me this: http://lurkingmusings.wordpress.com...peek-behind-the-double-helix-by-jade-kerrion/ which is a post about current scientific trends. When I had an Indian subcontinent writer promote her book she wrote me a piece of short fiction in which she introduced the main supernatural creature from her novel - the Yakshi http://lurkingmusings.wordpress.com/2013/03/27/vampire-month-beginnings-by-neelima-p/

I do the same when writing guest posts myself. For example, when writing a post for one blog to promote Transitions I discussed the issues surrounding the larger woman in fiction because my heroine is a BBW.

Basically, in writing a novel I reckon you must have researched something interesting, discussed some important issue or had something of note to discuss? Therefore talk about that. Provides the perfect excuse to lever in a link to your book without it seeming forced...

My personal approach is to look at what recurring topics each blog has (normally shown in tags) and try to provide something like that with a byline and link to book

I've written a few guest posts from a reader's perspective. I've also had a bunch of authors stopping by my old blog either for an event I hosted, or as part of a tour stop. Don't be afraid to ask if the host has a particular topic he/she would like you to discuss. If the blogger's creative, you'll get a few ideas thrown your way which may inspire you.

Usually for book tours, the authors would make their posts book-related. Sometimes, I'd see posts in a character's POV (think teasers). They've also covered setting (and how it relates to the novel--if it's an important factor), worldbuilding, a certain type/quality of character (which they would then link to either the MC or a secondary character in the story). Themes were the themes covered in the novel or series.

There were also fun and goofy posts, totally unrelated to the book. Those revealed a new side to the author. Don't underestimate those sorts of posts, either, since a quirky guest post has just as much ability to generate interest in an author's book as a guest post related to the novel can.

I think the most important part is to have fun while you're doing it. Jess Haines takes a unique approach to her guest posts by having her characters interact with each other in a brief interview. They always tend to be amusing.

Here's a blog post with links to a blog tour for a previous release of mine. Might give you some ideas. I give the blogger the choice of interview or guest post. Ask them if they want a giveaway to encourage comments and if there's a particular topic they want me to write about. I try to be entertaining while plugging the book. I try not to over schedule myself. I try for a variety of blogs. I try to make the guest post as perfectly formatted as possible to make it easier for the blogger.

Best of luck!