Give positive, as well as non-threatening, constructive feedback Source: Inspired by Satu Rekonen
Hang up two flip charts, one headed 'I like' and the other 'I wish'. Give the participants 5-10 minutes to silently write down what they liked about the past iteration and the team and what they wish was different (and how it should be different) – one point per sticky note. When everyone is finished, go around the circle and everybody reads out their 'I like' items and hangs them up. Repeat the same for the 'I wish' stickies. Either debrief or use the stickies as input for the next phase.
Written brainstorming levels the playing field for introverts Source: Prof. Bernd Rohrbach
Pose a central question, such as 'What actions should we take in the next iteration to improve?'. Hand out paper and pens. Everybody writes down their ideas. After 3 minutes everyone passes their paper to their neighbour and continues to write on the one they've gotten. As soon as they run out of ideas, they can read the ideas that are already on the paper and extend them. Rules: No negative comments and everyone writes their ideas down only once. (If several people write down the same idea, that's okay.) Pass the papers every 3 minutes until everyone had every paper. Pass one last time. Now everyone reads their paper and picks the top 3 ideas. Collect all top 3's on a flip chart for the next phase.
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 dotsor 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.