What do you read? What do you write? Who do you want to write for?
Several years ago when I was doing a bit of editing for an ebook company when I write to one of the authors and asked this question. "You're writing a romance. How many have you read?" The response was that this author never read a romance.
I thought back to the days when I decided to be an author. I'd been writing for a time, taking courses and studying books on writing but I really didn't know what I wanted to write. I set out on a reading binge. First reading classics and then moved to the modern books. Fortunately I'm a rapid reader. The Evelyn Wood course instructor wouldn't let me take the course. After a few reads I learned I'd never be a literary writer. I liked plots too much. I turned to the genres.
I read 100 romance novels, half contemporary and half historical. I read as many mysteries, fantasy and science fiction. Then I set out to begin writing. My first books were romances of the 'sweet nurse' variety and some of them sold. Then I turned to mysteries and some were rejected with great rejection letters. They finally all sold. So did the fantasies. Decided I don't have enough science to write science fiction.
The point of this is how can you decide to write books when you don't read or don't read the genre. Many writers write books because they love that kind of story. Others think they can do better than the ones they've read. But if you don't read and understand the conventions of the genre and of the particular house you're aiming for can you really expect to sell. Just think about the opening questions.