Quick excerpts from Wikipedia on consensus decision-making

The Quaker model:

1. Multiple concerns and information are shared until the sense of the group is clear.
2. Discussion involves active listening and sharing information.
3. Norms limit number of times one asks to speak to ensure that each speaker is fully heard.
4. Ideas and solutions belong to the group; no names are recorded.
5. Differences are resolved by discussion. The facilitator ("clerk" or "convenor" in the Quaker model) identifies areas of agreement and names disagreements to push discussion deeper.
6. The facilitator articulates the sense of the discussion, asks if there are other concerns, and proposes a "minute" of the decision.
7. The group as a whole is responsible for the decision and the decision belongs to the group.
8. The facilitator can discern if one who is not uniting with the decision is acting without concern for the group or in selfish interest.
9. Dissenters' perspectives are embraced.

One common set of hand signals is called the "Fist-to-Five" or "Fist-of-Five". In this method each member of the group can hold up a fist to indicate blocking consensus, one finger to suggest changes, two fingers to discuss minor issues, three fingers to indicate willingness to let issue pass without further discussion, four fingers to affirm the decision as a good idea, and five fingers to volunteer to take a lead in implementing the decision.