Collect what team members perceived as good, bad and non-optimal Source:
Put up three sections labeled ‘The Good’, ‘The Bad’ and ‘The Ugly’. Give everyone 5 minutes to note down one or more things per category from the last sprint. One aspect per post-it. When the time is up, have everyone stick their post-its to the appropriate labels. Cluster as you collect, if possible.
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.