Chris Hanley is a photographer who specialises in weddings and portraits. He likes to approach his work differently to other photographers and has recently started to do "cherish the dress shoots" a backlash to the harsh trash the dress shoots that are now popular. You can learn more about him and his work at Chris Hanley.
Here's his tip about reducing camera shake:
"It sometimes is difficult to get a high key look to a portrait on location in low light levels without risking camera shake. I get my subject to lean against a wall. I also lean the camera and lens against the wall too. I can handhold the camera at speeds of 1/20th second at about F/4 ISO 800."