I have some advice Phud....don't fuck it up!
JK - I have almost no experience in the real job market. However, I have been to many interviews. Most of the interviews I have been to have been a "dick" check. What I mean is the interviewer is checking to see if I'm a dick. These people are asking themselves if they could work with you, will you be a dick, are you professional, will you steal from the company, are you a drunk or a drug user. Even though they can't come out and ask you these things I guarantee they are in the back of their mind. Show them you are not by your demeanor. Project confidence without being a dick. Show that you are open without acting like a teenage girl. Let your intelligence come out though your answers, don't try to constantly prove yourself. Wear an undershirt so your pits don't sweat through your shirt. Put a handkerchief in your pocket so if you get sweaty hands you can dry them before you shake hands. Nobody likes shaking a cold wet fish. Take a leak before you go in...even if you don't have to. When seated, place both feet on the floor legs slightly apart. Hands should be on the armrests not gripping the ends of the chair. This shows openness and confidence. If you cross your legs you are too relaxed, and if you cross your arms it shows timidness. Look your interviewer in the eye, but don't stare like a rapist. Be sure blink but be conscious not to always look away when they look at you. Have a brief case or other business type satchel to keep pens papers resumes etc in. If you don't have one you can buy a cheap at staples, amazon, etc. Again, this shows professionalism and organization. If you are dressing in slax and a tie, make sure your shoes are polished. If you don't know how, you can buy a one step kiwi sponge at the grocery store. They work great and the shine lasts a few days. I carry one with me in my overnight bag.
These are things I have learned interviewing for aviation jobs, but I am sure they apply for any profession. Good luck!