What makes a great book cover
1. It’s unique
Many covers look similar. A guy, a gun, a cityscape in the background. Or a girl, an island, and the same cityscape. Or a thriller with blood dripping. Or romance with the silhouette of a couple kissing. These are all stock images that are used over and over again so they all look similar.
2. It’s not like other book covers
The best book covers have some element that is different from every other cover out there. The fonts are different, or the colors, or maybe there is something unusual about the image (like how “The Design of Everyday Things” has a hand holding a potato).
3. It’s memorable
A great book cover will be something you remember years later when you see it again on Amazon or in a used bookstore or whatever. I still remember book covers from my childhood even though I can’t remember what I did yesterday (or even this morning).
4. It tells you something about the story but doesn’t give it away
There are many ways to do this but here are some examples: The Great Gatsby - there is an image of eyes looking out of a window into nothingness but we don’t know who those eyes belong to until we read the book (the image changes slightly on each edition of this book as well). Catch 22 – there is an image of an airplane flying away from us and we can only see part of one wing so we don’t know if it is going up or down (and this also happens to be one of my favorite books ever). The Girl with the Dragon Tattoo – There is an image of yellow flowers on black and white paper so we don't know if they are coming at us or going away from us until we read the series and find out more about Lisbeth's past history.
5. Even if you hate it, you can't deny it's interesting looking
For instance, take any Dan Brown book ever published. They all have some sort of weird 3D effect where multiple layers move at different angles depending on which way you hold them while reading them on Kindle (I think). But no matter what your opinion on Dan Brown books is, his books always have very interesting looking covers that make them stand out among millions of other books sold every year.
6. It looks good small AND big
So many covers look good when blown up to poster size but then look pixelated when you see them small on Amazon or in a bookstore display case. For instance, take any James Patterson novel ever published (sorry James!). They all have photographic images usually involving guns and people running for their lives in front of blurry backgrounds that make it hard to tell what country they are in even though they were probably shot in New York City anyway because that's where he lives now after moving from Florida where he grew up because he hates hurricanes and wanted to live near family members who would help him hide when hurricanes came by since he never learned how to swim despite living near water his entire life since he was raised near bodies of water since his parents lived near bodies of water before moving back to Florida after selling all their belongings because they decided they didn't like New York anymore despite having been born there before moving back there after selling everything again because they changed their minds yet AGAIN about liking New York even though James has lived there for 50 years now since he moved back after deciding he hated hurricanes too much to stay in Florida anymore despite growing up there before moving back there again after deciding he hated living near family members who helped him hide during hurricanes too much even though...etc etc etc...James Patterson novels always