Leave distribution/selling to the publisher. Yes, it will be great if people can actually find your book in stores or online, so they can buy it. But it's the publisher's job to make the book available.
You can only sell so many books yourself out of your own car or doing book signings. The idea is not to sell the book, but to make people aware of it. Leave the selling to your publisher.
I can speak from my experience that my publisher sold WAY more books than I personal did or could. And I am not complaining. And now they have distribution, things will even be better.
That said, how are people going to know you exist? That's when author's promotion/marketing is important, especially at the local level.
Get yourself out there, talk about your book, do appearances, talks, radios, TV, magazine articles, talk to people, do book signings, etc. Get your name out there. You may only sell 20 books at a signing at your local store -- big deal, right? But those 20 people have now heard of you, and if they like your book, they will tell others, and they will know where to find it (make sure the store has some "signed copies" in stock). And words spread.
Get things published, too. Every time I get published (essays, short stories, reviews, etc.) it's linked to my book and my website. Will everyone notice and click on it and buy the book? No. But it's like advertising -- it's the persistent presence that makes it work, eventually.
Online communities such as AW is also a good place to be. I am not talking about drive-by promotions. But actually being part of the community. People get to know who you are, and they like what you have to say, and they're more likely to buy your book(s) even simply out of being supportive.
That's the kind of promotions you want to do, and not door-to-door selling. People are not going to buy your book if they have never heard of you. People are still not going to buy your book if they've just heard of you. But awareness can be long-lasting, and who knows? Eight months later, that person may hear your name again and say, "Guess what, I am going to get that book and find out."
That has happened to me.
But Llyod is right, too. Even if you promote yourself and your book, people won't be able to get it if it's not readily available in stores or online with significant discounts. That's why author's promotion alone is not good enough. Distribution is very important, but that's the publisher's job.
But to say, "Leave everything to the publisher" would be a mistake. After the book is published, the author and the publisher still need to work together to make sure that the book is out there, and people know about it.
