A rather fun exercise (and something I do compulsively most of the time) is to describe people you meet as characters from books. I had ample opportunity to amuse myself this way the past few weekends as I was down amongst a whole group of strangers working on a wedding. All you have to do is look at people with a sort of mental squint and capture it in words. Really, it's a great way to practice characterization--I prescribe one round of doing this at least once a month to freshen things up. :)
"She studied him as he stood on the ladder and fiddled with the lights on the stage. A tall, well-built young man. Young. And immature. She smiled to herself over the quick pronouncement, but she knew she was right. Only youth carried a splendid figure with that loose, careless gait. As he turned she caught sight of his face. He was not handsome--or was he? She could not make up her mind as to the whole of him, and as he dismounted the ladder and strode up the aisle she examined his individual features. Straight, white teeth and quick smile--very nice. Brown eyes with long lashes--lashes too long for a gent, but still pleasant to behold. A fine nose.
She settled back in her chair and bit her lip, eyebrows crinkled. Every feature in the young man's face was regular and handsome. How then, did he fail to please her?"
"The tall, lanky fellow lazed into the room. She'd been warned of him--told he was a charmer, a flirt, a wit. And as he made his round of the girls in the room, voice loud and bold and smooth, she knew what she had heard was true. Here was a man who demanded a full measure of attention from everyone in the room and who would get it or perish in the attempt. Yes, he was pleasant...no, she did not like him at all."
(And no--I don't generally find such fault with people. I examined quite a few more and found them charming. ;)