Have to agree with the latter posts. A slightly longer lens is usually better for portrait shots, or at least 'close ups'. A wider angle lens can give rather unflattering results by emphasising the size of the items nearest to the lens (usually nose and chin). For head or head and shoulders shots, anything around 105mm (+ or - a bit) is ideal. Using a slightly longer lens also imposes a little less on your subject, by keeping a little more distance between you/the camera and him/her; hopefully making them a little more relaxed