Driving Book Sales With a Little Help From The Friends (of the Public Library.)

I asked SuperLibrarian Cathy Camper about the relationship between library and commercial book sales. Once again, she shared some great information and advice.
1) Why does a librarian buy a particular book?
Most libraries buy from reviews. They don't have to be starred reviews, but any review in Publishers Weekly, Booklist or Library Journal counts (or local newspapers, blogs, topical reviews, say, if there's a blogger that just reviews mysteries). Libraries sometimes also buy when patrons...