Maurice Saatchi

Human nature is not amenable to prediction based on the trends or tendencies prevailing at the time. It is amenable to startling creativity of the kind practiced by great artists, directors, writers, musicians, actors, who know how to touch a chord in humans everywhere.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.

Hammer down product fundamentals first. Make sure you've got something that works before doubling down on promotion and marketing. Create a groundswell of organic support, and only then leverage PR and advertising to spread the word.