They say you shouldn’t judge a book by its cover, but readers do, because a well-designed and produced cover gives them a good idea of what’s inside. It tells them what genre the book is, it suggests a broad theme of the book, and it advertises the author’s brand.
Everyone knows a historical when they see it. There’ll be a girl in a long dress on the front. I myself am partial to pics of women in black crinolines, not to mention tattoo images. If it’s a 20th century historical it’ll probably be a photo of some sort. Historical romances will also have girls in frocks, but with a bloke. Modern romances (especially hot ones) often just have the bloke, usually shirtless. I think you know what I mean.
I find crime covers oddly unspectacular (no offence at all meant to crime writers) – and I read a lot of crime novels. They all look the same to me, so if it’s not a writer I know and love, naturally I read the blurb, then the first page to check out the style. Gone Girl by Gillian Flynn was like that. So-so cover, fantastic read, though it was more thriller than crime. Paranormals tend to look similar, too, ditto science fiction, and they’re like that for a reason – so readers know what they’re getting. So the message is: do the same as everyone else (ie, you don’t want to put a ‘True Blood’ type cover on your rural romance), but better, so your book stands out.
A survey I saw a while ago reckoned that if a reader isn’t looking for a particular author, they’ll choose a book based on a) the cover, then b) the blurb, then c) the first page. So there you go. Covers are vital.
One book I’ve read lately, just because there’s a cute wee mouse wearing a cape on the front, is Let’s Pretend This Never Happened, a memoir by US humourist blogger Jenny Lawson. I wouldn’t have bought it without the mouse. It’s a good read, too.
Of course, if you’re traditionally published, you more or less get what you’re given, so you have to trust that your publisher knows what they’re doing. In my experience, they do. At a workshop at my publisher the other day, the designer said they send cover concepts to booksellers for feedback, because booksellers know what readers like and want.
It never does any harm to talk to your local bookseller.