As a publishing professional, here's something I see all the time: an author writes a blog post like this:
Headline: The Secret to [X Thing The Author Wrote a Book About]
Article: Have you been wondering how to build a house/lose fifty pounds/fly a kite (etc.)? I have the answer for you: buy my book!
Does this look familiar to you? The author is holding back. They have promised the readers an article and instead offered them an advertisement. They don't want to give away too much, for fear they will have nothing left to sell. I have some news for these authors, and they won't like it.
Hold nothing back.
I'm not saying you should post your entire book, as is, for free on the Internet. But I am saying, when you write a blog post or press release, don't leave out "the good stuff."
I know there may be a tendency to think "but if I tell them how it's done, they won't buy my book." This is an impoverished mindset: deep down, the author thinks they only have a limited amount of content to share, and they got it all out of the way in their book. Readers can see right through this mindset. Especially in the 21st century, when good free advice is just a click away. When they see you holding back, they believe your insecurities. They believe your expertise is so thin, you have to hoard it. When you share freely, they see someone who knows what she's talking about. They believe you've written this particular book because you are overflowing with insights, and telling a story you are uniquely qualified to tell. Which approach do you think leads to more fans?
When you hold back, it creates an adversarial relationship with your readers, a tug-of-war over how much they get of your expertise. On the contrary, when you give away your content, your followers become very loyal, and they want to give you money.
Even if you put your entire book online, and gave away all your secrets, they would still buy the book because:
The best way to make sure this mindset isn't affecting your marketing efforts is to write the best content you can for your readers. After you've written your press release or blog post, look at it as a stranger would. Ask yourself if this is the kind of thing you would bookmark if you happened upon it. Better yet, is it the kind of thing you'd want to post to Twitter and Facebook, so your friends can benefit from it too? The answer to this question is why marketers are always harping on the phrase "content is king!" If you want to gain followers and write blog posts that go viral, you must write content that holds nothing back. Write first and foremost to share targeted, helpful advice and you won't have to sell your book. Your fans will sell it for you.