Using Lean Coffee™, "participants gather, build an agenda, and begin talking. Conversations are directed and productive because the agenda for the meeting was democratically generated." - leancoffee.org
Step One: Before the retrospective starts the facilitator should set up a kanban board with three columns:
Step Two: To start the retrospective the facilitator should explain how the technique works and provide the team with the timebox for the retrospective (1-2 hours, depending on the size of the team).
Step Three: Ideation. The facilitator should hand out sticky notes to the participants and tell them the timebox for this phase (10-15 minutes should be enough). Participants should keep their sticky notes private so that participants aren't biased by each other's ideas. When the timebox expires, the participants should place their sticky notes in the "To Do" column on the kanban board.
Step Four: Grouping. Since many sticky notes will likely contain related (or even identical) ideas, participants should group sticky notes into logical themes. Participants can use markers to draw circles around related sticky notes. The facilitator should announce the timebox (10-15 minutes) and encourage the participants to stand up and move from poster to poster to make this part of the retrospective interactive and fun.
Step Five: Dot Voting. The facilitator should announce the timebox (5-10 minutes) and, if the team has never used dot voting before, explain how it works:
Step Six: Discussion. The facilitator should announce the timebox for this phase (45 minutes to 1.5 hours should be enough). The facilitator can optionally choose to timebox the discussion of each individual sticky note as well (to 5 or 10 minutes). The advantage of this approach is that it tends to keep the conversation on topic and moving at a faster pace. As discussion starts for a sticky note, the facilitator should move the sticky note to the "Doing" column on the kanban board. When discussion is over for the sticky note, the facilitator should move it to the "Done" column on the kanban board, and then move on to the next sticky note in priority order.