I was asked recently by a good friend of mine to discuss book covers and I thought it would be good to share what I have learned while working with Amazon and the Kindle.
If you are self publishing, then you will have to either hire out the cover to an artist or create the design yourself. A good cover should cost anywhere from $50 to $200 depending on who you choose to work with. They should be willing to do revisions with you, accept payments in installments, and understand your needs and goals as a writer. You can find cover artists by doing a web search or by posting a wanted ad on Reddit in either Writing (asking for people to recommend a cover artist) or For Hire (tagging your post as [hiring] Cover Artist and then posting a bit about your rate.) There's also Fiver which will charge $5 for a simple cover, but you will most likely end up with something that looks like a template.
Covers should advertise and allude to the content of the book without being too on the nose or too abstract. Remember that print books, which are objects, can do things with covers that eBooks can't. "Puzzle" covers where you have to pick the cover up and inspect it to find meaning, optical illusion covers, bold wording covers, and covers that are %90 author name, are not effective on the eBook platform.
One of the best ways to communicate the contents of the book is through the font that you choose for the title itself. Photoshop has tons of fonts by default and there are plenty more available for free online. The letters themselves should evoke a feeling. I use Cooper Standard for most of my titles and A. J. Cosmo because the font communicates softness and whimsy. I want to comfort and dazzle children and parents. Be sure and line up your text as well. You want visual symmetry. Use the guide tools in your photo editing software and be picky about getting it all to line up and look even. Make the font big enough that you can read it from a distance. Set the viewer at %50 and walk to the other end of the room. You should still be able to read it legibly. Do it again for %25. You should still be able to read it.
Most of the time people will only be viewing the thumbnail of the book either in their digital library or on the landing page for the item. You actually have to work on the Kindle to get the cover to come up full screen. So be creative and eye catching, but not too clever. Amazon also compresses images that are uploaded to it. Just from experience, the compression software they use doesn't handle flat color well, particularly red, and this causes digital artifact "noise" to appear on your cover. A solution to this, oddly, is to add more texture to your background. Play around and don't settle for something sub-optimal.
You ideally want to upload a .tiff that is twice the size of the default cover size. Amazon resizes images uploaded to eBooks down to 600x800 pixels. So for covers I usually make them 1200x1600. Your image will still be compressed down, but it will look crisper since the software on their end had more information to work with. Also note that you can change the shape of your cover by uploading a different proportion of pixels. Dimensions like 800x600 will give you a landscape oriented cover.
Covers can be tricky and there are way more tips and tricks to share. If you have any specific questions I'd love to help. Just tweet me @ajcosmokids and I will be happy to help you in any way that I can.
Tomorrow, I'm going to be going through a step by step example of "fixing" a cover that you have already created. We will look at my book An Alien in the City, critique it, and see if there's something we can do to improve it.
All my best wishes,
A. J. Cosmo