A good preparation starts with facts, a clear conversation goal, and a defined framework. The more sensitive the topic is, the more important structure becomes.
Collect concrete observations: Who was involved, what happened when, how often it occurred, and what effects were visibly present. During this process, separate second-hand information from your own perception. Also define what you want to achieve in the conversation: clarification, stopping a certain behavior, protecting a person affected, or the next steps needed to resolve the situation.
Plan the conversation confidentially, give it enough time, and avoid interruptions. Prepare opening phrases, follow-up questions, and boundaries in case the employee responds defensively, emotionally, or trivializes the issue. That way, you don’t walk into the conversation improvising—especially when it can quickly spiral out of control.