This is a quite nice retrospective method I learned from agile42. Prepare the definition of done of your team by writing each point on a single line and put three columns besides every point. Paint the columns in red, yellow and green. The now colored columns stand for "We did that well" (green), "We did that ok" (yellow), "We didn't to that very good" (red).
In the retrospective every team member puts a dot in the colored column expressing his view on how good the team applied this point of the DoD. The result looks like this:
Now you can pick the 3 points with the lowest overall rating, discuss them (20 min timebox each) and develop optimisations for them.
You can do the same for your working agreements.