This can be simply asking each person to state both a frustrating thing and a good thing about the meeting. After the meeting the person who took the minutes needs to write them up and, if possible, send them out to those who attended, or who usually attend. The minutes are a record of the decisions that were made. Every point in the discussion does not have to be written down. Having minutes saves a group from re-making decisions, because you have a record of past decisions.
Minutes are also valuable when it comes to making the next agenda.
Consensus means that the group takes actions that everyone consents to. This does not mean that everyone is in perfect agreement, but that everyone can live with the decision. In rare instances a person decides to block agreement because an action would violate one's principles. But the concept of blocking consensus can be used for manipulation. Generally members should strongly be urged to accept the group's judgement.