Making your clients feel comfortable starts with understanding how it feels yourself. When was the last time YOU stood on the other side of the camera and had your photos taken?
Put your camera down. Put on something you feel hot in and get your photos taken.
Don't feel photo-genic? Neither did I. For YEARS. Then I quit worrying about how fat I looked or whether I had a double chin, and just enjoyed the moment. Getting your photo taken is actually quite fun. really. ;P
Photo Credit: My second shooter, Bianca