Ty Cohen talked about "Growing a 5-figure a month Kindle Business: Getting Attention & standing out from the crowd".
When he wrote his first book, the advantage he had was knowing the marketplace and who his target audience was.
What is his marketing strategy? He markets his specialty books to his target audience through the channels that they're most likely to use such as a specialty magazine or newsletter, an e-newsletter, a website, Facebook, to name a few.
He has an interesting approach, which seems to work really well. Find out what your reader wants, what your audience is interested in and give them that content. Whether you're a fiction or a non-fiction writer, look at what your competition is publishing, read the reviews, and find out the positive and negative aspects of the books that they're focusing on. Then use that valuable information and apply it to your books.
On the marketing side, it's also important to find out information about your readers. Run ads on Facebook (start by spending the smallest amount), on YouTube, Bing... Diversify your means. And don't do just what others are doing. Reach out of the box! [I like this!]