"His expression is keenly alive with self-interest, which makes him appear blind and alert at the same time."
I'm sorry, but isn't that line kind of awesome? It's from Tessa Hadley's "The Trojan Prince," in the November 15th issue of The New Yorker. It's actually quite a simple tale of a young man who thinks he knows everything about what he wants, but would have a hard time putting any of those wants into proper words. He's easily angry and yet internalizes his frustrations, and he finds himself in the middle of a bizarre (cousinly) love triangle.
But that's the line that sticks with you. Here is some of the rest of Hadley's description of James McIlvanney:
"He's only sixteen, despite the man's overcoat and the new tweed cap. His hair is jet-black and very straight, and his face is composed of strong fine lines, clean and clear and exquisite like his pink-and-white skin; his eyebrows are as well-shaped as a woman's, his curved lips pressed shut as if he were holding in important news. The jut of his cheekbones and jaw is masculine enough -- strained and resilient. His expression...."
I marvel at writers with such ability to describe what a person actually looks like. I would think the challenge is to translate enough of your imagination to the page so readers are on your train of thought, without literally being like, "Think of Ben Affleck, right? Like, ok, I'm thinking of a guy who looks like him, but maybe with closer-knit eyebrows and a slightly less pronounced chin? Ok, ok, ok -- now we have our hero. Now, the heroine... Well, you know Barbra Streisand in "The Way We Were?" Ok, this girl looks the opposite of that!"