Most beginning writers - and I was the same - are like chefs trying to cook great dishes that they've never tasted themselves. How can you make a great - or even an adequate - bouillabaisse if you've never had any? If you don't really understand why people read mysteries - or romances or literary novels or thrillers or whatever - then there's no way in the world you're going to write one that anyone wants to publish. This is the meaning of the well-known expression "Write what you know."