The best fiction-writing teacher I ever had was Luke Whisnant. One day I was in his office, reviewing a story I'd written for his class, and he passed along an old piece of writerly advice: "You can tell a lot about a person by looking at his shoes."
Back then I owned one pair of shoes: black Converse high-tops. They were gradually disintegrating; I'd worn them every day for years, in all kinds of weather, and there were holes in the sides and the fabric was tearing away at the toes. I was ashamed of them; cheap as they were, I couldn't afford a new pair, and mainly I just hoped nobody would notice them.
"I notice you tucked your feet under your chair when I said that," Luke continued, not missing a beat. I blinked in surprise. He was right; unconsciously, I had done exactly that.