Here’s one detail that seems to divide professional genre publishers and many self-pub authors/inexperienced small presses/vanity publishers:
Cover font.
Specifically, a hard-to-read script font.
Font matters as much as imagery and composition. For e-books, the cover may be one of the most important investments an author or publisher will make. The ‘thumbnail’ sized or small-format cover (seen on Amazon, B&N, ARe, and other online vendors) has to manage these tasks in only a few seconds of a reader’s browse time:
Catch the reader’s eye: interesting color choices, strong composition, action scenes, symbols, etc.
Announce the genre: is it epic or high fantasy, science-fiction, romance, magic-realism, contemporary urban fantasy, etc?
Tell us the title and author: who’s claiming responsibility for this thing? In addition, the book cover might sport a series title or tagline.
Many script fonts look amazing at full-size, quite readable and evocative. When shrunk, they are squiggles.
Cover designers: if you can’t read the title, author, or tagline on a smaller-sized cover image, don’t rationalize your gorgeous font or make cosmetic changes like backing it with more contrasting mist or moving it to a less effective but clearer cover location.
Change fonts.