Blog exchanges are one idea suggested for authors who want to widen their audience, and blog commenting is also recommended. An interesting idea that I came across was to comment in "do follow blogs." These are blogs that allow posting in comments and allow posting links to your site as part of your name --AND-- when the search engine hits this site, it is permitted to "backtrack" the commenters to their home page.
What this does is sort of "spreads the word" and makes your book (or art) and your name easier to find. The advice ALSO said to set YOUR blog to "do follow."
I see both good and bad ideas running here. On the good side, this may increase your visitors. On the bad side, many of them are spammers and they're just coming to ad links to their sites and make themselves look important.
There are lists out there of "do follow" blogs, but some investigation showed that many of them look like sales sites and not true blogs and are likely to get taken down as spam sites. I think some sort of middle ground here is needed -- and the answer might lie in the "blog roll." Of course, the problem then is getting onto someone's blogroll. But that's something for another time.
Do Follow Blog List | DoFollow Blogs