Books get judged by their covers. They do, it’s unfair, and it happens anyway, so plan for it. When laying out your cover design, you’ll need to allow for the barcode box (defined by the printer, on the back side of the book). You’ll also need to know how many pages it is, so you can design a cover that is precisely the right width for your novel; that is, your cover design is precisely wide enough to fit the width of the spine that the printer will make. That’s why the cover design is step 11 instead of step 1.
Full color, full cover photographs are very eye catching and work VERY well. If you don’t have a talent for it (or the equipment for it), take a look at websites that host high-pixel digital photography that’s free under the Creative Commons License for commercial use. You’ll need at least 300 pixels per inch in order to get a sharp picture for your cover.
Look at book cover in your book’s genre. Bright colors? Washed out picture? Monochromatic? Where’s the title placed? How big is it? Is there a design element in the cover that clues you into a series tie-in? What kind of font is used for the title? What kind of font is used for the author’s name? Is it different? Is there any other text on the cover? (If the author’s name is bigger than the title, realize that they’re doing that because the author’s name is a selling point – your name probably won’t be. Don’t take your cues from that.) If you are using a person on the cover to represent a character, you’ll want that same model for all the books in your series, so make sure you can be consistent across the series that way.
Consider combining photographs to make your cover unique. If you don’t do that, at the very least, use some image effects on the picture so that if someone uses that same photo for their cover, your cover will still be different.
And when you look at a hundred covers in one genre, you’ll be able to tell what most of them have in common; make sure that your cover has those things, too. If you just HAVE to break a rule, make sure that you are only breaking ONE rule; all the others must be followed, or you’re going to confuse your buyers. If just one thematic rule is broken, then it’s still a part of the group, just a little off. But if two rules are broken, it’s not necessarily within the genre, and potential readers will shy away.
Oh – one more thing about using faces on your cover. I’ve been endorsing Creative Commons photos from the beginning, but there’s a drawback to those as well. People are really good at remembering faces. Really good. So if you choose a model for your nice, sweet mid-teen coming of age novel, someone else can come along and use that exact same picture for their raunchy erotica novel … and readers will assume from the covers that there is some connection between the two. Even if you aren’t using photos of faces, you should combine a few photos in some way and use some graphic effects to distinguish your novel from all others that may use that particular photo in the future; it also allows you to make a thematic tie-in across several novels to indicate a series.
All this requires sources and software; check out my Resources page for a few websites for pictures and software to make it perfect for your book.