While most people are happy to repeat the adage that you can’t tell a book by its cover, there is no doubt in the minds of most publishers that people do in fact buy books because of their covers. Knowing that fact, however, still leaves open the question of what an effective cover is. Having participated in innumerable cover discussions where people expressed directly opposing points of view, I’m well aware of the subjectivity that goes into a cover choice. I also know that styles and tastes change regularly, so that what works for one season may soon be outmoded.

Still, there are some practical guidelines publishers should keep in mind when working with cover designers.

Make it all legible. Having spent a fair amount of time writing copy for dust jackets, direct-mail projects, and other kinds of packaging, I’ve engaged in the tug of war that seems inevitable between writers and designers. Writers want more copy. Designers want more space, more visual drama, and more, in a word, design. Often, the publisher or marketer must mediate.

Beyond the issue of words versus space lies a more important consideration: legibility. If the title and subtitle of a book are hard to read, whether on the front or the spine, the cover has failed in its basic purpose. Effective design aids the reader. When considering a cover, I always take a few steps back to see what it looks like from five or 10 feet away. If I can still read the title and subtitle, it passes the legibility test.

Design it so that it reproduces clearly in black and white. If black-and-white photos of your books are ever featured in reviews, flyers, catalogs, or space ads, you want the cover image to be clear and the title to be readable. This is an obvious point, but it is often forgotten during consideration of cover designs.

If you’re looking at color comps of prospective covers, take them over to your black-and-white copy machine and see how they reproduce. Your machine copy will probably lose a lot more detail than a printed photo, and it will probably smudge contrasting hues more too, but looking at it will give you a way to imagine what a photo of your book will look like on newsprint. Is your beautiful, subtle, evocative cover still interesting? And is it still legible, or did the bright-yellow title disappear into the surrounding field?

Check for legibility at thumbnail size. Photos of covers are often reproduced in very small sizes but are still required to convey essential information about the book. I’ve seen lots of catalogs and ads where the book titles appear only in tiny cover reproductions but not in the catalog copy. If the title isn’t legible in the cover photo, readers can’t determine the name of the book described in the accompanying copy, and the catalog listing or ad has been a complete waste.

Test the cover on a computer screen. This one is a recent addition to my list, but given the growth in Internet bookselling, it’s an important consideration. Fortunately, you can rely on reasonable color and contrast, for the most part, so this test is easier to pass than the black-and-white test and is probably passable by any cover that aces the thumbnail test. Nevertheless, you should test your design on your screen to be sure.

Create clear and credible cover copy. For many shoppers, bookstore browsing consists of a narrowing process. They are drawn to the featured displays at the front of the store, or perhaps they want a book on a particular topic and browse only that area. Or, being in the store and having a general desire to find something entertaining, they meander among the sections that consistently attract them. They pick a book off the shelf because the title sounds interesting or they know who the author is. They glance briefly at the cover–registering a fleeting positive or negative impression–and they turn the book over to read the back cover.

For publisher and author, this is an important moment. Some browsers will decide that this is not the book they want and put it back on the shelf without ever having read a word of the actual contents. Others, who find the back cover inviting or interesting, will proceed to open the book and sample the contents. Good cover copy draws your potential reader in.

So, what works for cover copy? This naturally varies with the kind of title at hand. Most fiction titles rely on a simple description of the setting and plot. Certain kinds of nonfiction call for third-person descriptive copy; others work best with copy in the second person and present tense. In general, observe the basic principles of good sales copy. Use simple, clear, direct language and emphasize what’s strong, new, or different.

Although seemingly overdone, testimonial quotes and/or reviews provide credibility and reassurance to your potential buyers. Whenever you have a strong quote from a recognizable source, use it. However, I usually don’t recommend including anonymous quotes, such as “from D.C. in California,” nor do I favor a back cover that uses only quotes. Your strongest cover will combine credible recommendations with some descriptive copy that summarizes the legitimate value of the book as strongly as possible.

David Cole provides business plans and brokerage services through his consulting firm, Gemini Marketing & Communications (www.geminicole.com), and is principal of Bay Tree Publishing (www.baytreepublish.com). He can be reached by phone at 510/525-6902 or by e-mail at dcole@geminicole.com.

This article is adapted from The Complete Guide to Book Marketing by David Cole, available for $19.95 plus $5 shipping and handling (NY state residents must add sales tax). Order toll-free from 800/491-2808; by mail from Allworth Press, 10 East 23rd St., New York, NY 10010; or via www.allworth.com.