I can tell straightaway when a fiction author has little interest in or passion for their subject material, and crafted a story for the sole purpose of hitting a “market segment”. I have real contempt for such writers.
No matter what kind of writing you do—short stories, books, children’s lit, screenplays, stand-up bits, whatever—don’t ever approach it as though you’re trying to please an audience. Don’t ever write what you think people want. Don’t ever write about something you think is popular. Because invariably, it will suck. And it will suck hard.
Write to please one person and one person only: yourself.
Which is to say, write the kind of book that you love to read. Write the kind of script that you want to see on the screen.
If you write something you don’t like, you’ll get bored with it and shelve it, or throw it away and start over, because you don’t want it to see the light of day. And rightly so; if you’re not interested in the story, no one else will be either. But if you write something that thrills you, mark my words you’ll finish that fucking thing. You’ll find a way. And you will work your ass off to polish it before it leaves your desk.
Obviously there’s no guarantee it will reach an audience. But at least you didn’t write a dispassionate tale about teenage vampires, for example, simply because teenage vampires are a popular thing. You wrote something that pleased you immensely, based on topics and themes and interests that tickle your brain and grab you right in the guts. You wrote the kind of story you’d pay to read if it had been written by someone else. Which means it’s likely that a load of other people with similar interests would pay to read it as well. What’s more, savvy readers can always tell the difference between derivative crap written to editorial order, and prose by someone who clearly wrote the story solely because they loved it and wanted it told.
And that’s good news for you.