Keep to the agreed-upon topic and do not get off on another agenda. A diversity of opinions is both healthy and stimulating. See differing viewpoints as an opportunity for learning and deepening the dialogue. The process is meant to be collaborative and not confrontational. Someone may have a specific perspective, but is is important not to be locked into it.
People can disagree without someone having to be wrong.
The purpose is to share. Always speak from direct experience rather than giving advice. In circle, you are holding what everyone is saying without having to arrive at an overall conclusion. Let the paradoxical linger until it naturally progresses into a larger view. Allow yourself to be comfortable with loose ends.