Although it may be true that ‘You can’t judge a book by its cover’, it is often just a split-second glance at the cover image which decides a potential reader whether or not to look inside.
A good cover is one that immediately attracts attention of an appropriate kind. ‘A picture tells a thousand words’ but these may be different words for different people. This is illustrated by the so-called ‘Gestalt’ images which can be seen in two ways: a face or a vase, a young woman or an old witch. Elsewhere I’ve described a bad experience when I showed a picture of a trapeze artist during one of my talks; this was intended to represent courage and joy, but one member of the audience thought it was a woman hanging herself.
Does your chosen cover image accord with the content of the book, and convey the corresponding mood of adventure, mystery, romance or relaxation? Colours are important, and all colours have psychological qualities, which can be modified by the shades and combinations chosen. Red, orange and yellow are usually stimulating; green, pinks and blue are calming; violet and indigo are spiritual. Cultural background affects the interpretation, for example in my own European tradition the colour of mourning is black, but in various other parts of the world it is white, purple, yellow, blue or grey.
The lettering on the book cover needs to be reasonably large and clear, otherwise the title and the name of the author will not be legible from the thumbnail image often used on computer screens.
The cover image for the ebook version of my recent book Persons not diseases on Smashwords was designed with professional help. I was pleased with it, but when it came to self-publishing the same book in paperback on Amazon CreateSpace – the first time I had used this system – uploading the existing image was beyond my limited computing skills, so I opted for making a brand new one with the easy-to-use templates provided. The two covers are completely different – personally I like them both, but would be interested in readers’ comments about which they prefer. You can view the Smashwords one here and the Amazon one here.