Yes, I can verify that some of my personal marketing efforts have given my book a boost where it might not otherwise have gotten one and helped me find an audience.
Yes, authors should do whatever they can to promote their books and get their names out there.
There is only so much one writer can do. And I while I think that any marketing effort that helps even one person find your book is worthwhile, I don't think any number of blog posts, school visits, appearances or giveaways will do as much as for a book as one big push from a publisher.
A mere five years ago, I was just a consumer of books who went to my local bookstore every few weeks and purchased five or six books at a time. I never went to a signing. I never read a review beyond the occasional review in Entertainment Weekly or the Los Angeles Times. I never talked to a bookseller. And looking back, I can see how my choices were dictated entirely by store placement. Simply put, I bought what publishers were pushing.
In five short years, I have a completely different way of buying books. I "listen" to internet chatter, actively seek out reviews, explore similar books online, and read the first few pages. I love the fact that there are more opportunities for books to be "found" and break out than ever before, that store placement isn't the end all and be all for book sales. But there are also more books being published than ever before, making it harder for a book to get noticed.
The bottom line is it is hard to break out, even with a big push from a publisher. There is no secret formula for writing or marketing that will guarantee sales. But there are some things that I've learned along the way, that I've tried to incorporate into my own marketing plans:
1. Write the best book I can: Wait, doesn't marketing involve promoting the book after it's written? It does, but a quality book is the best marketing tool a writer has. A good book will sell the next one. Good reviews generate word of mouth. Conversely, if a reader doesn't enjoy the book, chances are they won't pick up your next one. That's not to say that everyone will like your book (they won't) but you want to give yourself the best shot you can to gain fans.
3. Put yourself out there: Marketing means getting out there and making connections. Talk to booksellers, go to conferences, get online.
4. Don't break the bank: swag is nice, but it's expensive. If you can afford to give away a few things with your book design or brand, do, but if you can't, I think that this is an area that can be cut.
5. Leave it to your publisher to market to stores: Publishers already have a sales team and a network of booksellers and librarians. Trust that your publisher is marketing your books to librarians and retailers. Don't try to shortcut that process or make booksellers uncomfortable by giving them a hard sell. Offer to do local events, but never attempt to force yourself or your book on a store.
7. Write the next book: I know, I already said this, but the number one thing you can to ensure further sales is to writer another book. And then start all over again.