When it gets down to it, books have to attract readers to get read. And you attract readers with what they see.
So the book covers need to catch the eye. The cover needs to stand out with a unique or enticing image. The cover has to rock.
Getting a good artist or photographer helps. But the other thing is that the labeling - the title, the author - has to be both legible and eye-catching too. Anything too bland - a basic Sans Serif like Arial, or a basic Roman like Cambria - and people won't notice. Anything too cutesy or gimmicky - Comic Sans, Papyrus, Papyrus Sans (ye gods) - and people will recoil.
So I'm working with the artist for my next work, and trying to come up with a feasible cover text for the title and author.
My personal preference for the author font is Flareserif (similar to Albertus). I suppose I *could* use the same font for the title, but most times you'll notice publishers don't go that route: the title has to stand out a little more. Have a little more flair to it.
So I'm juggling between these fonts for "Body Armor Blues":
Glaser Stencil D:
If anybody suggests Helvetica I will hurt you. That costs money, dammit.