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.
If your team has a tendency to see obstacles outside of their team and influence and primarily wants others to change, you can try this activity:
Draw a big rectangle on the board and another rectangle inside of it, like a picture frame. Hang all complaints and grievances that surfaced in previous phases into the frame.
Now comes the interesting twist: Explain that if they want anything in the outside frame to change, they will have to do something themselves to affect that change. Ask the team to come up with actions they can do. Put these actions into the inner rectangle (near the outer sticky they are addressing).
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.