Everybody sums up the last iteration in 3 words Source:
Ask everyone to describe the last iteration with just 3 words. Give them a minute to come up with something, then go around the team. This helps people recall the last iteration so that they have some ground to start from.
Collect some news headlines in advance and take them to the retrospective to serve as examples. Try to gather a mixture of headlines: factual, opinion, review. Place the headlines where everyone can see them. Hand out sticky notes. Give team members 10 minutes to come up with their own headlines describing newsworthy aspects of the sprint. Encourage short, punchy headlines. Stick the completed headlines to a whiteboard. If any cover the same news item, combine them. If any are unclear, ask the reporter for details. Vote on which news items to discuss and analyse in more depth.
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.