"If you’re a writer, it’s fair to assume you’d like to write a bestseller. In my 12-plus years of experience as an editor for a major publisher, bestseller status is the Holy Grail of the writing trade, and it’s not just an ego thing. Hitting the bestseller lists is an emblem of the impact a book is having. Bestsellers are not just about fame and money; in fact, writing a bestseller guarantees neither. They are about having an impact on society. Bestsellers are world changers. By definition bestsellers are rare. So what does it take? How do you make it onto a bestsellers list?" (http://www.authormedia.com/little-known-secret-writing-bestselling-nonfiction-book/)
If we knew the answer to this question, we would all have given up our day jobs to become full-time writers. Meanwhile, we will try to analyse the skills required to write and market popular fiction as well as the je-ne-sais-quoi that bestsellers from various popular genres seem to have.