The facilitator should be welcoming and friendly, but relatively ordinary and not overly talkative. The participant and website should be the focus of the interview and test, not the facilitator. To create rapport with the participant, the facilitator should be an ally. A good way to do this is to make fun of the situation and reassure participants that their experiences in the test will be helpful. Another good technique is to ask more like an apprentice than an expert, so that the participant answers your questions, for example: Can you tell me more about how this works? and What happens next?.
Since you want participants to feel as natural and comfortable as possible in their interactions, ...