Designing conversational interfaces is a complex task, but opinionated design principles can help push past the hype and create practical and usable experiences. These principles should guide clarity and reduce ambiguity in chatbot interactions. They are not mere truisms, but rather strongly-held opinions that an entire team agrees on, representing a north star for everyone to aim for. Key principles include "Don't pretend to be a human", "Keep it incredibly simple", "Respect the chat medium", "Optimise for the end user", and others, which should be applied consistently and methodically to create effective conversational interfaces that improve the end-user experience.