So you can’t always judge a book by its cover. That may be true for actual content but you have to make your book stand out from all of the others available. Choices include photographs or other images. Don’t just download an image you find on the internet. The owner of that image could sue you if you don’t have their permission to use it … Sorry I know that picture of Benedict Cumberbatch or Bradly Cooper would be ideal for your cover but without their permission you can’t use it! If you try their representatives will issue a cease and desist order. Amazon may ban your book and even ban you and you might be liable to pay damages to those actors.