Set up a 'retrospective mailbox' at the beginning of the iteration. Whenever something significant happens or someone has an idea for improvement, they write it down and 'post' it. (Alternatively the 'mailbox' can be a visible place. This can spark discussion during the iteration.) Go through the notes and discuss them. A mailbox is great for long iterations and forgetful teams.
Collect what to start, stop, continue, do more and less of Source:
Draw 5 spokes on a flip chart paper, dividing it into 5 segments. Label them 'Start', 'Stop', 'Continue', 'Do More' and 'Do less'. Participants write their proposals on sticky notes and put them in the appropriate segment. After clustering stickies that capture the same idea, dot vote on which suggestions to try.
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.