I read a great article called "How to Talk to the People in the Bookstore" by Melissa Lion. I was hooked at the beginning when she swooned because Khaled Hosseini "smelled so damn good." He's one of my favorite authors, and of course I've swooned from good-smelling men a number of times myself. I also like her reaction to someone who is offended by the presence of a particular book.
I'm not sure many of these recommendations could be adapted to a library other than looking patrons in the eye and saying hello. We've stressed that this year, along with name tags and other ways of being more personal, more approachable. I think students are still scared of us no matter what we do, but we can keep trying.