I've done blog tours, but I didn't see much payoff from it. In some cases, the host of the blog didn't do any promo for my post whatsoever; it was all on me. And I have trouble wrapping my head around the concept of having to promote my promotions, so the blog tours just plain didn't work for me. I had the same problem doing guest appearances on other authors' blogs and hosting other authors on mine (I would promote the guests I hosted, but they wouldn't bother promoting their posts.)
On the other hand, I've had a lot of success doing blog *hops*, because everyone involved promotes the hop, and I sign up for ones that have a central site listing everyone's links. I promote my own post, which links to the central site, and everyone else does the same with their own posts, and everyone wins.
For 2013, I've decided to only do blog hops and guest spots on either group blogs or non-author blogs (like review blogs, etc.). Some of the review blogs and industry blogs with great traffic offer guest spots and interviews to authors; I just signed up to do a guest post on my birthday in June on the All Romance Ebooks Cafe, for example. And some of the sites that review my books have asked if I wanted to do an interview/guest post to go along with a review they were doing.
Other promo that has worked for me: Facebook and Twitter. I know it doesn't work for everyone, but for me it does because I have *conversations* there. Of course I post new release links, and once in a while I pimp a backlist book there, but about 90% of my posts and tweets are along the lines of "Wow, it's cold out!" or, "Uh oh, Tobias and Kyle are fighting" (which was a status/tweet I posted the other day about the book I'm currently working on). I also sometimes share/retweet other authors' stuff, which builds some goodwill and some reciprocity. When one of my favorite YA authors, who has something like 10K followers, retweets my new release announcement because I did the same for her (even though I only have 410 followers)...that's huge.
I second whoever recommended Love Romances Cafe. The Yahoo loop gets a lot of traffic, and they also have a Facebook group with specific promo days (for example, Monday is general promo, Wednesday is "post your best cover", etc.) Dawn Roberto, who runs the joint, also reviews books, and she recommends books to others when she likes them.
Dawn Roberto also runs a promo service, which won't work for everyone, but I signed up with her because I know how far her reach extends and her rates are incredibly reasonable. I pay her $15 a month to post promo about my books in various online venues; yes, that's something I could do myself, but she has more connections/venues available than I do, and having her do it frees up time for me to actually write my books. There are a lot of promo services/companies; some are well worth the money, and others aren't, so if that's something you'd want to do, make sure to do your research. (I chose Dawn because I know her fairly well online, and because other authors who use her services gave her high recommendations.)
The Romance Studio has frequent "release parties" (at least 2-3 a month, usually) where authors can pimp a book or two; they also have longer parties for things like Valentine's Day or their anniversary. There's a ton of traffic to their party site; you can offer a giveaway but don't have to; and they promote the parties heavily as well as the participating authors all promoting it. I've gotten a lot of attention and some sales through those parties.
Another advantage of The Romance Studio parties is that people who sign up for the prize drawings can opt to be included in authors' newsletter mailing lists. I take full advantage of that; I offer a prize each time, so I'm sent a list of all entrants, which includes whether they're willing to receive newsletters. I do a monthly newsletter through MailChimp, and thanks in large part to the TRS parties, I have over 400 subscribers. Many of whom actually read the thing... For some authors, doing a release-only newsletter might work better; my subscribers tell me they prefer the monthly one, and since I have a new release almost every month anyway, it all works out. I don't just pimp my books in the newsletter, though. I also include a message, just something chatty like "Wow, that blizzard dumped a lot of snow" or "My daughter is mourning her pet mice" so readers see me as a *person*, not just an author; I include a short excerpt that's exclusive to the newsletter; and I have a contest every month.
I used to question the wisdom of "build your backlist", because that wasn't working for me at all, but in the past few months it has been. So if you use your backlist to help boost readership, be aware it might take time to actually show results. (My first romance was published in March 2009, and I didn't start to see the "backlist bump" results until July of last year; my first YA was published in January 2010 and I'm still waiting to see the backlist pay off. For those who like numbers, I have 39 published romances, including freebies and stories in anthologies, and 16 published YA books.)