An author I recently met at a writer's conference (again, that's a future post - why agents go to writer's conferences - it's not what you think), asked if I could give some pointers on marketing. Honestly, I could write a book on this one, but the bottom line is that in today's book world, the author has to do most of the marketing, even if s/he gets a six figure advance.
Before you've even finished the book, you should join the professional writer's organization of your genre (every genre has one from sci-fi to children's books to the American Society of Journalists and Authors). If they don't take associate memebers, lurk. Read their websites; see if you can join chats. Learn about your genre.
Start a blog. Write about what you are writing. Be part of a commmunity. Do this by reading other writers who are writing what you are writing. Read their blogs and comment. If they're published, and you like their work, leave a review on Amazon.
What comes around goes around in the writing world, so if you are not part of a community, you will not be included when you think it's your turn.
When you've sold your book, really become as active a member of said genre organization as you can. You will be taping published authors further up in the food chain for quotes and information. You can also get quotes from authors whose work you admire by emailing them on their sites and/or leaving comments on Amazon. You need quotes. You will have to pay back, when the time comes.
Start getting quotes about your work from published authors in your genre. Get them at least four months before publication.
Put together a list of the local media - newspapers, radio and TV (meaning cable), your alumnae newsletter - and write your own press release about your book. Try to come up with a hook - something that will make it stand out beyond LOCAL WRITER PENS NOVEL (unless, of course, the novel takes place in your locality).
Visit every book store in the area and tell them you will do a reading/signing or even a how-to-get published (you just tell your story) presentation on any day they want you.
Also (unless you are writing very graphic or explicit material) call the local school board and see if they want you to speak. Libraries usually want speakers too. Local Church, rotary, Lions, ect. clubs often will let you speak too. If you get a few speaking engagements outside of a book store, it might be worth your while to order a box of your books from the publisher at the author's discount (usually 40-50% off) and sell signed copies at the gig.
Keep writing that blog. Link to every author and writing-related site you can. Get your own website.
Your publisher will only send your book out for reviews to a list of reviewers they will not share with you. If you are obsessed about make sure you get a copy to The New York Times, Associated Press, USA Today, ect., call, get the name of the book reviewer for your genre and send it yourself (USPS has a great media rate to keep the cost down) with a personal note about why you want them to see this. Make sure you include your cell phone number and email address.
Get your friends to give you good reviews on Amazon and Barnes and Nobles.
If your book relates in any way to a current event (it's a horror novel, Halloween is coming and it recalls your teen years in said county), write an op ed piece or a letter to the editor where you can a) mention the book (with your blog or website) or sign your letter b) Jill Smith, author of WHEN HEAVEN WAS HELL.
That's the basics.
There's much more, but let's get some feedback and suggestions from your peers. Perhaps we'll have a part 2?
Oh, and by the way, don't expect your agent to do this work for you. Her job is to sell your book and guide your career, not to do your p.r. Even if s/he represents the god in your genre, get your own quote (but tell said god that you have the same agent, which should help).