Just like any other kind of interview you want to dress professionally (we had a man interview wearing black shoes and white sports socks, YES your dress code matters! Yuck!) Do what you need to feel confident and act confident, not nervous. Be confident when asked something you don’t know and don’t be afraid to say “I don’t know but I know where to go to find out.” Honesty is important, we all know when someone is bluffing their answer and it never looks good. There’s a start. If you know you can do the job, act like it. I didn’t “know” everything when I interviewed to be a network admin, but I was confident I could learn and was honest about what I did know and what I could do and my willingness to do whatever it took to gain the knowledge I needed..