Sure, you can find a photo and slap some lettering onto it, and call it a cover. Lots of people do. And there are definitely some photos that need very little added to make a reasonable cover.But chances are, the photographer wasn't thinking of book covers when he took the photo. So it's your job to convert his work to your purposes.
A book cover doesn't need to tell the book's story. In fact, it shouldn't. If you tell all about the story on the cover, you're probably telling the reader all he wants to know. If you satisfy him, he's done. No need to read your book. So instead, you want to intrigue him enough to want to pick it up, open to see if he wants to read more. This might tell you what's wrong, or one of the things, about my first example. But bear with me.
First, let's talk about why some great ideas don't work out.
Let's say you've done something I've done: decide to write a book set in Hawaii, then go there to research. (As an aside, that started out to be a wonderful, exciting trip, and would have ended that way-except that I came down with Asian Flu and spent the second half, too sick to do anything. The photo I'm using here was just about the only good one I took. An incredible view. Hubbubs stopped the car. I opened the door, stood up, clicked, and moaned loudly as I crawled back into the car. Closed door. Remember not much else.)
Nice shot, huh? But look again. What does it say? "Blue-green-white-black. Wow, pretty. Click. Drive on." Narrow it down and focus on that cliff into the sea. Give it an edgy dark border, and you have something more dramatic. But you still have the wrong message for a book cover. It still says pretty much what was happening to me that day. Drive on to the next scenic overlook. Get a pic you can look at sometime later when you're feeling better.
But pretending you haven't noticed that yet, let's proceed.
It says the author is a totally naive amateur who hasn't even bothered to guess at what the reader wants to read.
Why? First, The lettering is awful. Not so much that the fonts are bad, but that they are the wrong size, misplaced and unreadable. Second, the dark shadowed border seemed like a good idea, but in reality it's a contradiction to the beautiful day that was so bright, my eyes hurt. Flu or not, it was that bright. Beautiful day just doesn't turn into ominous day all that well. AND nothing here except the title says mystery and danger.This is clearly not Hawaii Five-O. It's Gawking Tourist on Vacation. Helen Does Hawaii. A coming of mid-life crisis age story, maybe. But even then, not even the roar of crashing waves says tension and conflict, action, character change, any of those things that would make a reader want to know more. Sorry. pretty tourist shots generally don't make it for book covers.
Nice texture and aging. Sophisticated yet rustic colors. Really intriguing silhouette of a woman. BUT not the right woman, unless we're aiming for a somewhat different message. I'd do something different with this if the story is a sort of Shirley Valentine on Oahu/suspense. But let's say it's not, and just cut her off. First, I enlarge the image by making its height 9". Then I use the "Canvas", not the "Image" tool, check the middle, far right box of the 9-box square, and set the width at 6". That cuts off the image on the left only, and gives me my standard proportions.
Hm. Now it reminds me of a Winslow Homer watercolor my mom owned years ago. Wonder if that's why I like it?
This is exactly the same lettering from the pretty sunshiny day design, gone from awful to just right. Enlarged, placed right. The word "by" removed-it carries just a hint of that amateur taint we're trying to avoid. Same coloring except that the name font color was taken from the sky background (which actually needs to be a little lighter color, I think.)
And did you notice, I didn't make any attempt at all to keep the darkening border on the left side? Why? Well, sometimes I'm not really sure why I make artistic choices. This time, maybe it's a matter of balance, of opening up to the far horizons of ocean and sky. The focus is actually on the palm trees in the wind, and the wind also comes from that open sea to the left.
What, you want the gleeful ex-wife back? All right, but it takes some more work. and you can see it's got a different cast to the story. Set the width to 6" with "Image", then use "Canvas" set for 6"x9", with the existing image set at middle bottom. You have to fill in the top 3". Duplicate the existing top and move it upward on that new layer you made by duplicating. Then use the clone tool with a fairly large, fuzzy brush to fill in the empty space and cover up the original top edge. Because the woman's silhouette is so prominent, I emphasized the "Ex-Wife" protion of the title by centering and enlarging it. Notice everything else also has to take different positions in the design. That balance thing again. And the author name needed more of a stroke surrounding the letters because it's up against a smaller scale background that has a lighter color. More work but still just one image.
I think if I were doing this cover, I would make the sky colors, especially the muted turquoise, deepen toward the top more. And of course I'd play around more with the lettering. You should always do that. Sometimes the best designs are those that pop up utterly out of the blue.
I'd say if you're learning anything from me, try to learn whimsy. Let yourself play. Follow a whim and see where it takes you. That's where you'll find your very best covers.