The document provides advice to avoid common mistakes in body language when interacting with upset or angry clients. It recommends maintaining a calm, sincere, and concerned facial expression and tone of voice. Specific behaviors to avoid include negative facial expressions like smiling or looking away, using a sharp speaking tone, wrapping arms defensively, having an improper body position like being too close or relaxed, touching the client, insulting, swearing, eating or chewing loudly, and acting slowly or lazily. Proper body language is important for resolving client issues and portraying a positive image of the organization.