I think the most important thing we as writers can do is figure out how we define what success will mean to us and focus on that.
I think Paris smells not just sweet but melancholy and curious, sometimes sad but always enticing and seductive. She's a city for the all senses, for artists and writers and musicians and dreamers, for fantasies, for long walks and wine and lovers and, yes, for mysteries.
When writers stop to sharpen pencils or get up and make coffee to procrastinate, they still stay in their heads with their characters. But when you zip over to read email or check your Facebook page, you get zapped out of the fictive dream. It's brutal on my writing.
You can write the best book you can, and that might still not be enough. Appeal isn't something that most writers can't strive for or identify. It's something even the best agents and editors can't always identify.