What could sub-groups improve when interacting with others? Source:
Identify sub-groups within the participants that interacted during the iteration, e.g. developers/testers, clients/providers, PO/developers, etc. Give participants 3 minutes to silently write down what they think their group did that negatively impacted another group. One person should be part of one group only and write stickies for all groups they don't belong to - 1 sticky per issue.
Then in turn all participants read their stickies and give them to the corresponding group. The affected group rates it from 0 ('It was not a problem') to 5 ('It was a big problem'). Thus you get insights and shared understanding about problems and can select some of them to work on.
Divide a flip chart into boxes headed with 'Start', 'Continue' and 'Stop'. Ask your participants to write concrete proposals for each category - 1 idea per index card. Let them write in silence for a few minutes. Let everyone read out their notes and post them to the appropriate category. Lead a short discussion on what the top 20% beneficial ideas are. Vote on it by distributing dots or X's with a marker, e.g. 1, 2, and 3 dots for each person to distribute. The top 2 or 3 become your action items.
Let team members appreciate each other and end positively Source:
Agile Retrospectives who took it from 'The Satir Model: Family Therapy and Beyond'
Start by giving a sincere appreciation of one of the participants. It can be anything they contributed: help to the team or you, a solved problem, ...Then invite others and wait for someone to work up the nerve. Close, when no one has talked for a minute.