When selling your book—which is your primary job after writing said book—you should keep this in mind. If you've got legitimate contacts (read: people you actually know, and not famous authors you met at that party that one time) in the industry, make use of them. Meet for dinner/drinks. (Commandment #7: Thou shalt pimp thyself.) This goes for other authors, agents, publishing folk, book store staff, you name it. You're going to want to do local author events once your book drops, and there's no better way of greasing the wheels for that than by getting to know the staffs of your local stores (chains and indies) ahead of time.
Now, some of you might not exactly be social butterflies and may well say to me, "but Eric, I'm a writer—let me write and leave the schmoozing to the professionals!" And yes, if you are super painfully shy and honestly believe you will do more damage by trying to work these connections yourself, you might want to consider letting publicity handle all of this. But I have a feeling most of you don't fall into this category, so I say to you: soldier on. You wrote a great book. Now sell that book!
To quote Daniel Menaker: "And you have to understand that even though you are formally separated from the literal sales force, you are still above all fundamentally 'in sales.'" True, here he's talking about editors and the editorial team, but it's just as true for authors. Yes, you're on the writing "team." But you're also on the sales team.