‘Decide what to do’ is the fourth step that you take in Retrospectives. An important tool that can help with you making such decision is Short Subjects.
So far in the retrospective, the team has gathered data and generated insights, short subjects help to convert this into an action plan. The moderator puts short subjects on top of a white board (or an online tool, if remote) and the team works together to put all of their suggestions in the right categories.
A very common set of short subjects is – start doing, stop doing, continue doing. The team can categorize all the feedback that they have received into these three actions.
Here’s an example,

Check more articles on Agile