For a manager about to conduct an interview, or a staff member to be interviewed, The appraisal interview video and self-study pack (for appraisees) will ensure both sides understand the objective of an appraisal. It takes a look at the whole appraisal process, and provides a number of valuable behaviour do's and don'ts to follow.
In terms of overall behavior, people should be adequately prepared, should listen and ask questions, and must concentrate on performance and not personality. In terms of performance, they should be specific about successes and failures, agree on future objectives and a course of action together, and be constructive and not destructive.