The promise comes before the decoration
A cover is a promise about the reading experience, aimed at a specific shelf. The first test of any design is whether a stranger can name the genre and tone in about a second, next to the current covers in that category. A beautiful cover that signals the wrong genre recruits the wrong readers and earns the reviews that follow. Study the live bestseller grid for the category, extract its shared cues, and express them with an original image rather than a copy.
One focal idea, ruthlessly kept
Strong covers commit: one symbol, one figure, one landscape, one typographic move. Each added element competes for the same glance. If the story has many marketable elements, choose the one that best carries the promise and let the blurb handle the rest. The test is squint-simple: shrink the cover and ask what single thing a viewer sees first — if the answer is nothing in particular, the composition has not decided.
Thumbnail legibility is where covers pass or fail
Most buying decisions start in a search grid where the cover is smaller than a business card. At that size, thin scripts, low contrast, and fine detail vanish. The title needs the strongest contrast on the cover and a clean field behind it; the focal object needs separation from the background. Check the actual thumbnail beside competing books before publishing — and after every major typography change.
The technical floor is not optional
A professionally designed image still fails if the file is wrong: soft resolution, missing bleed, an incorrect spine, text in unsafe zones, or the wrong color mode. Platform specifications are exact and checkable, which makes them the easiest part to get objectively right. A bounded technical check can verify dimensions, ratio, and small-size contrast; genre fit, originality, rights, and taste still need human judgment.