Yesterday I was reading a 1940's detective novel and I was struck by how usefully -- as well as how often -- the writer used cigarettes to convey emotion. Characters light cigarettes, put out cigarettes, share cigarettes, search for cigarettes, and a dozen other gestures, all of which can be made to convey emotion. It was a handy device that is no longer useful since (1) it's become a cliche and (2) far fewer people smoke, and thus so do far fewer characters.
More inventive gestures, however, are still a good way to convey emotion -- provided that the writer has established a context for them. Does that character's slow blink indicate nervousness, flirtation, thoughtful pondering, or lying? A slow blink can signal any of these. Which do you intend? Do the other characters correctly interpret the gesture? What is their context? All of this, done correctly, can create much texture in fiction.
Context, of course, is always cultural. My family is Italian; they gesture constantly and largely. A sweep of the arm can punctuate nothing more dramatic than "I slept really late today." For another family, a large sweep of the arm would be reserved for "Get out of my sight forever!" Still others would utter that sentence with a totally still body and cold eyes.
All of this was on my mind because in the book I'm writing, I wanted to have my character make an obscene gesture. But I can't -- I don't know what, in this fantasy world, the obscene gestures are. Back to the world-building stage. I only know they won't involve cigarettes.