A vital ingredient for successful planning is an agreed and practiced decision-making process as part of the group’s governance system.
Whichever model is used, all group members should understand it and the workshop facilitator should help participants to follow it. Some models which a group might consider:
Decision by majority of members, generally only useful for very large groups which would preclude full active participation in the core process outside of workshops.
Decision by full agreement of all members.
Decision reached without significant objection of any members rather than full positive support, where objections are acknowledged and tackled. A primary example of this approach is Sociocracy, which extends out to organising processes for the group to use when researching options. wikipedia.org/wiki/Sociocracy