Mostly it's been the noise I hear around about the book, or the name of the author rings a bell, or (if I'm feeling whimsical) it can sometimes just be the title. The only thing I tend to pick up religiously even if I've never heard of the author is anything Scandinavian - I'm thoroughly, totally and absolutely addicted. And anybody local - especially new Australasian authors - I'll read all their books on principle :)
I'm with Gerald on this one. But I have to admit, I shy away from most literary mysteries. If given half a choice, I'll almost always choose noir/hard-boiled/pulp, unless it's a new release from one of my favorite authors. Lately, I've been reading my way through the Killer Year authors, with some Bruen/Starr/Rhoades/thrown in.
If it's an author or book I've never heard of, the cover comes first. Then I read the back blurb and, the real test, the first paragraph or page. Then I flip to the middle and read a paragraph or two. If the writing is good and the voice is strong, I'll pick it up. Honestly, though, I'm pretty picky. I tend to stay with tried and true genres/authors or with suggestions from other readers that I know share similar tastes and sensibilities.
Sometimes titles will make me pick up a book - but they won't make me keep hold of it. If a book with a really really great title says on the back... "A serial killer is stalking the streets of St Mary Mood and leaving a verse of Amazonian love poetry wrapped around a chess piece carved out of brie tucked in the ear of the victim which has been sliced off using a silver potato peeler. Our intrepid amateur sleuth solves the crime with the assistance of only her overly large nostrils and her pet aardvaark Samuel, who's really the ghost of Joan of Arc, then the book is going back on the shelf.
I'm attracted to really bizarre titles. I wouldn't have discovered such wonderful books as NIGHT OF THE AVENGING BLOWFISH (John Welter), THE LUST LIZARD OF MELANCHOLY COVE and ISLAND OF THE SEQUINNED LOVE NUN (Christopher Moore).
I love Christopher Brookmyre's titles and Charles Willeford's. Mark Haskell Smith's MOIST is one you can't say any way other than...well...with moist delight. Charlie Williams, Barbara Seranella, Victor Gischler, Bill Fitzhugh and Steve Brewer all have great titles. Some titles just grab you by the leg as you pass the shelf.
Others I don't care for so much. I don't particularly like titles that start "Murder in The..." or "Death in..." or "The Something Something Mystery"
Covers - I'll wander round the bookstore and anything with an appealing cover will get pulled off the shelf. Again, I'll only buy it once I've read the synopsis or the first paragraph. But covers that make me pull the book off the shelf in the first place might be things with bright covers - a lot of comic thrillers have bright covers - Carl Hiaasen, Bill Fitzhugh, Mark Haskell Smith. I rather like something quite plain. Anything with an old pulpy type cover. Things on the cover which tend to make me put the book back - syringes, eyeballs dripping blood, shattered glass. Most books with pink covers (the exception to the 'bright' rule). Trees are a bit boring :o)
If the cover say "The new Dan Brown / James Paterson / John Grisham / Janet Evanovich / Patricia Cornwell" it's probably a no for me.
Titles and covers work in getting me to pick up the book in the first instance for authors I don't know, but the things that get me to buy a book are if I've heard good things about the book from people, if the synopsis on the back looks like something I might like (the words hard-boiled, noir, warped, bizarre, funny make my heart beat faster; the words serial killer, gory, signature, hospital, feisty, conspiracy, and love interest...don't). I always read the first couple of paragraphs and that settles it one way or another. So the writing is the thing that makes me read a book and keeps me reading, but there are a number of things which might get me there.
The title and the back blurb (and sometimes the author's name, like Karen I like finding new translated authors). Then I dip in to the first para then at random. I'm not too bothered about the cover.
Donna - I agree with you about certain words turning me off - kidnap, conspiracy, grail usually do it! As do most crime novels where the investigator has an implausibly personal connection with the killer.
My apologies if this is a repost--I'll come back later and delete the extra. Ning seems to be having problems lately.~~
If it's an author I know and enjoy, it's an automatic buy, as long as I've got the money.
Otherwise, I'll look at titles and authors, and if I see something that piques my interest, I'll pull it down and look at the cover. The art usually tells you something about the particular subgenre of the book. If it's a subgenre I'm interested in, I'll read the back, and if my interest is still piqued, I'll open it at a random point and read a bit to get a feel for the author's writing style. If I like the author's style, I'll carry the book around with me for a while while I look at others, and if after all that, I'm still interested, I'll buy the book.
I read widely and by mood so what leads me to choose a particular book this week may not work next. But -- location is a major draw. I have forced myself to finish books I did not like just to learn more about the setting, or the occupation of the main characters. I like being entertained but I also want to be taught something new. And I respond to catchy titles, enough to pick up the book and look at it, and certain covers are appealing, although I can not describe what makes me choose one over another. Some covers are dead giveaways for me to avoid, especially if there is anything looking like lovers with windblown hair or something concerning food or cute shops. When a book is talked about here or on one of the reading lists where I check in, that sets me up to remember the title or author when I see it later. I find that mystery fanatics are very good at leading me to the books I want, or want to avoid.
For me it is generally the blurb or a recommendation from an author I enjoy. If Parker or Sandford like it I'll give it a try. Of course it is almost always from a library so it costs nothing to check it out. My purchases are limited to an occasional paperback of favourites or classics that I have not previously seen.