Speak up when most people disagree
Back up your concern with a specific reason
The team wants to start sending all orders through a new supplier next week. You know you haven’t yet dealt with any returns through them. Your view can be valuable to the team even if you don’t have evidence that there’ll be a problem with returns.
Start by saying where you see things differently. “I suggest we start with a small trial order. We haven’t checked their returns process yet.” Then ask whether anyone has already checked the terms. If the team has new information, take it into account. If they decide to go ahead anyway, you can ask to agree in advance on how you’ll assess the change.
Practice. State your concern in two sentences. In the first, say what you propose; in the second, give a specific reason.