Put candidates at ease: Interviewing can be stressful, so do your best to help candidates relax. Make sure each candidate is greeted and escorted, if necessary, to the interview location. Start with low-key questions.
Don't judge on first impressions: We've all met them -- people who don't make a great first impression but end up being great employees. To make sure you don't overlook these diamonds in the rough, withhold judgment until you've had the chance to thoroughly evaluate a candidate's capabilities and potential.