This is a stupid-sounding topic. We all know how to chat with people in unique fields, like astrophysics, training Arabian stallions and, er, writing. You just flail around for something interesting to ask, and come up with, maybe: Is a black hole really eating up our galaxy? Or, are there any Arabian female horses? I know you can do better, but I think those aren’t half-bad, given how little I know about astrophysics and horses.
But if making small talk with horse trainers and other odd-jobbers isn’t all that hard, why are folks so often uncomfortable chatting up authors? I watch people at conventions talk to prominent authors, and it isn’t pretty. I get a few whoppers myself.