I'm composing my first portrait and I've decided on a model. He has a large, squarish face. I could do either a head and shoulders portrait, a half length portrait, or a full length one. Props that I have include a wide, patterned, white one-seater couch, a black swivel chair, a drawer that is a little below waist height, and some glasses, teapots etc.

I need some tips on how to bring out his character. (facial expression, pose, etc)
The subject likes is not too expressive or emotional and likes to use the same few phrases when he speaks. He has few hobbies, and spends his free time on the computer and watching tv. He is short-tempered and can get angry and frustrated easily, and may blame others. He has a good sense of humour.
I can either have him dress in a suit or a plain white t-shirt and jeans. He dresses casually most of the time, except when he is at work.