To use conversational interfaces in prototyping, you need to follow some best practices and steps. Start by defining your goal and scope: what problem are you trying to solve? Who are your target users? What are their needs and pain points? What are the key features and functions of your solution? Then, design your conversation by mapping out how you will greet users, guide them through the conversation, handle errors and exceptions, and end the conversation. Use scripts, storyboards, or flowcharts to do this. Next, build your prototype with the right tool and platform. Use simple and clear language with an appropriate tone and personality. Test it internally and fix any bugs or issues. After that, test your prototype with users. Explain the purpose and context of the test to them. Observe their reactions and responses as they interact with your prototype. Ask them to rate and comment on their experience. Finally, analyze your data and iterate. Identify what worked and what didn't, what users liked and disliked, what they understood or misunderstood, what they expected or suggested. Use these insights to improve your prototype and test again.