Almost anyone can facilitate a usability test; all it really takes is the courage to try it. With a little practice, most people can get quite good at it. Try to choose someone who tends to be patient, calm, empathetic, a good listener, and inherently fair.
Don’t make me think
Being an expert in online usability Krug gathered his experience in a wonderful book. This summary of key thoughts will help you to remember most important principles and laws.