How To Choose a Novel Like a Birdwatcher

Birdwatchers have a term, GIS, which is borrowed from the military and is short for General Impression and Shape. If you ID a bird based on GIS, you're not focusing so much on particular field marks--wing stripes or a circle around the eye--as you are on your instinctive reaction to the bird's size, shape, color, behavior.GIS is how I choose books. I read some reviews but almost no back covers. Although I can be snared by an awesome premise, I often don't know the premise of the book when I start reading. Sometimes I know something about the author, or I just know that it's an author who's well-loved by other readers I respect. Sometimes I know almost nothing except that the book has a "look-and-feel" that makes me comfortable. I know the marketing teams at the publishing houses work hard on these "look-and-feel" impressions, so there must be other people like me who are GIS choosers.The crazy thing is, it works way more often than not. And when I stray outside my GIS comfort zone because of a fun premise or some other lure, I am often disappointed. But overall, I think I am less-often disappointed than my friends who depend more on rational decision-making--reading back covers and reviews, choosing a premise that snares them, or simply reading the next book by an author they've loved in the past.One problem is that e-books offer many fewer cues for the GIS chooser. I'm pretty sure that even things like weight and gloss are signals for me in a book store, and without those extra signals, I'll probably have to depend more on other signals. I'm already leaning a lot (and successfully) on the Tweets, Web sites, and blogs of the author.How do you choose books?