I have stuttered all my life. And thank you so much for asking this question. I agree with keeping eye contact. Also, the more relaxed the person I am speaking to is the more at ease I feel. Also, having some very soft background music on, like classical music, can help fill in any pauses in conversation and lessen tension. Thank you again for reaching out and being willing to learn something new to support your potential employee. If more people, like you, were willing to learn new things and consider other points of view the world would be a much better place.