Many don't know how to give an interview. A good interview should be about 30 - 45 minutes long. You should go in prepared, and you have already looked at the applicants application.
How often does this happen? It's almost non existent. When is the last time you DIDN'T sit for 10 -15 minutes while your interviewer takes his time reading your appy? Trust me folks this is not part of the 30 minute interview.
Me personally....I was thrown in the deep end when I was a cook. My boss couldn't get to it, on time and didn't want the applicant to wait any longer. That's another non on, making the applicant wait longer then 10 minutes.....odds are they have stuff to do too.
Notice how the applicant is dressed. Are they wearing holey jeans and a t-shirt, or did they take pains to look presentable. I'd go with the presentable everytime. One time at Denny's a 16 year old applicant showed up for an interview in a 3 piece suit. This is rarely seen, that and the sparking personality, he got the job, hand's down.
Your job as the interviewer is to make sure there are no questions asked. It sounds corny but start with telling about the history of the company. Everyone should know how it started.
Give some aptitude questions, get the person talking, draw them out. this way you can get a read on if they can do the job. Sometimes you are better off hiring someone with aptitude then someone with experience. Ask questions, what did you love about your job, what did you hate. If they come up with a pat answer, and fast.....well if it were me, I wouldn't be apt to hire you. Come up with something original, even if it takes a few minutes, then they put some thought into it. even if they say it right out fast, it means the prepared for this interview. this is a good thing.
At some point,l talk about the job, and exactly what is expected. there should be no surprises. Mention the benefits of working with the company. Do you promote from within, do you have a 401k, insurance....tell them. At the end you should give a short tour of where they will be working if hired, where to eat(break room)and restrooms. Always take the time to escort them out.
If you say you will get back to them in a couple days, or a week....please do it. This is a professional courtesy. Did you like it when people said they were going to call, and never did?