This is the time I actually use the mantra fake it til you make it. Be interested, ask them lots of questions, try not to focus on your fears, have a plan down, have a list of things you want to go over with them, and keep telling yourself if it doesn't work out there's always next time. Consider it good practice.
Be honest and open, easy to approach, smile, pay attention to the little one.
I get so stressed out at every single one. Waiting for them to show up is the worst feeling, all that anxiety builds up. My stomach keeps doing flip-flops until they've been here a few minutes. By then I can usually tell if they're approachable and easy to get along with or if I'm wasting my time; either way helps me relax. Most of my dcfs come from family referrals so that's usually encouraging and a good starting point. I always give them a folder with handbook, policies, contracts, other print-outs and tell them to go home, read, discuss, email or call with questions and then we can talk some more. I also encourage them to visit other providers to make sure what I offer is what they want for their child.
Good luck!! I'm a terribly shy introvert so I can understand the stress each interview brings on.