Personally I do the following things:
- Understnad the requirement. Based on requirement prepare list of topics you need to cover. Also you can prepare list of questions for each area. If you are experienced interviewer you may not need to have topics list and questions as you automatically can ask just looking into resume and requirement.
- The most important thing is go thru the candidate resume before you start the interview otherwise you may not judge the person correctly.
- Try to avoid questioning in the areas where the person didn't mentioned in resume or he is not comfortable. If you extend those topics you may get answers "dont know" etc., Rememeber you are trying to understand what he knows and not what he doesn't know.
- Try to understand person's learning capabilities. He may not remember everything so, for such questions if you give some clue he should able to pick up if he is good learner.
- Make the interview environment more friendly by doing some of the following things: offer the interviewee some
water, introduce your self etc.,
- In the end give him a chance to ask questions if he have any.