I enjoy doing headshots for friends or for work. Setup is simple and fast, and catching a good image usually takes less than three minutes.
There are many ways to take clean headshots. I use my 70-200mm Canon lens, stretched out to maximum magnification, with ISO usually around 400, and f-stop set at the bottom of the range - 2.8, in this case - for that great, blurred background. All of the images you see on this page were taken with my camera mounted on either my monopod or tripod, for greater stability. Ask your subject to face the camera slightly off center - either by turning his head slightly or by orienting his shoulders around 45 degrees to the camera. Try to pick a background that contrasts with the subject's hair color to prevent the top of the head disappearing. The final "trick" is to work either with ambient light or golden low-sun light.
That's all you need to know. Oh, and get some good-looking models, such as you see here!