Listen with full concentration and take notes. Listen for repetitious, consistency and conviction. Look for the passion with which an applicant pursues outside interests. This is threatening, he or she may ask too little for fear of being eliminated, or too much, expecting to be bargained down. It is best to ask about salary history.
Most people are truthful about what they earn.
The interviewer should also be truthful about the salary history. Tell candidates about the next steps. They want to know what will happen next and when. Don't leave them hanging. Stick to the plan, and communicate as promised up to the very end.