When I attended the writing seminars at CapClave, they basically said to market both.
Next year, my middle-school-targeted book, The Seven Sisters will be coming out from OakTara and even before its release, I've been pushing it as I am going to deliberately make an assumption OakTara will be depending upon me to do the lion's share of promotion.
Taking a page from Karina Fabian, editor of Infinite Space, Infinite God, I made a short one-minute promo video and put it on YouTube. The program I used was Windows Movie Maker that comes with the version of the Vista OS I have (some versions do not come with it). The program is very easy to use, but it still took me three tries before I learned some of the shortcuts and tricks available to me. I deliberatly did not want a complex video, but short (exactly one minute) with consistent fades between the pictures. You can see it here.
The pictures were commissioned from an artist years ago (it took me almost a decade to find a publisher for this book) and the music is royalty free from incompetech. However, the music is not license-free and there are terms for use.
By the bye, google for royalty free pictures for graphics to use in your own video. Windows Movie Maker does allow for the illusion of movement so your pictures need not appear as static as mine.
The text plates I made in MS Paint saved as .jpeg files for easy drag-and-drop into the video.
So I played with it and made it the way I wanted. Uploaded it to YouTube (very easy to do though you must have an account there) and then using Window Movie Maker burned a very nice DVD with a pretty menu.
This is not as complex as it sounds, but if you are all thumbs with technology, ask friends and family for assistance.
KEEP THE VIDEO SHORT. One minute is a good length.
Next, I work on giveaway promotional business cards.
I would appreciate the rest of you contributing to this topic on how you market your work and yourself. Karina's example has been awesome and well worth emulating. I also have gotten a lot of mileage out of Guerrilla Marketing for Writers: 100 Weapons to Help You Sell Your Work, by Jay Conrad Levinson, Rick Frishman, and Michael Larsen.