The trick to dealing with an anxious client is two-fold. First, remain calm. Nothing good happens otherwise. You are the expert this person hired. Behave it. Imagine slicing your finger open cutting a bagel. You freak out. You wrap it all up. You go to the emergency room. Do you want your doctor to scream when she sees it, or to look at it and very calmly say “Let’s take care of that.” Be the calm doctor.