An excellent way to perform a retrospective is to ask the Five Whys: Ask why five times to understand the root cause of a problem.
Here is an example:
Problem: The server is slow.
Why #1: Because it is running out of memory.
Why #2: Because the code has a memory leak.
Why #3: Because it was not tested properly.
Why #4: Because we do not have good automated tests.
Why #5: Because we have not received training in automated testing.
I am an agile coach and an angel investor. As an agile coach, I have consulted and trained at dozens of companies. Major agile coaching engagements have been with Paypal, State Street, edX, Carbonite, and Symantec. I typically begin with culture first and then proceed to process improvement and business results. I believe in a non-confrontational, non-coercive approach to change in which people are invited to be and act in a new way. This takes the pain out of agile transformations.
With Rob Rubin, an online education pioneer and the Founding VP of Engineering at edX, I recently created DemingWay.com, an online agile education portal that we plan to grow until it has the best agile content and the best learning platform.