Prompts for Book Covers - Nano Banana 2

That reframing changes what you write. Instead of “a detective standing over a body in a rain-soaked alley at night”, you get further with “a single wet streetlight, deep shadow, muted teal and amber, empty frame”. The second one is not a worse description of the book. It is a better description of a cover, because it has one idea in it and that idea survives being shrunk.

Working covers are overwhelmingly built on a single dominant element against a simple ground: one figure, one object, one shape. Ask for that explicitly. Say the subject is centred or offset, say the background is flat or plainly textured, and say where the emptiness is — “upper third empty”, “wide clear area above the subject”. You need that space, because the title and your name are going into it later in a design tool, not into the generated image.

Those are conventions, and the practical move is to name the convention rather than describe it in adjectives. “1960s Penguin paperback design”, “modern flat vector illustration, three colours”, “gouache painting on cold-press paper” each pull an entire visual tradition into the frame. That is more reliable than stacking words like moody or dramatic, which drift.

Generate at full size, then look at the result scaled down to about two hundred pixels tall — the size it will actually appear in a store listing. Most covers fail here rather than at full resolution. Fine detail turns to noise, low-contrast subjects dissolve into their background, and a composition with three competing focal points becomes a smudge.