Joining a project.
WHAT TO DO FIRST
Get it running locally.
WHY
Nothing else is possible until you can.
WHAT TO ESTABLISH
How a request flows through the system Where the entry points are Where data lives What external systems it depends on How it is deployed
WHAT TO READ FIRST
The routing definitions.
WHY
They are the map of what the application does.
WHAT TO DO NEXT
Follow one request end to end, through every layer.
WHAT TO NOTICE
Conventions in use, whether documented or not.
WHAT TO FOLLOW
Those conventions, even where you would have chosen differently.
WHY
Consistency matters more than any individual preference.
WHAT TO ASK ABOUT
Anything surprising, before changing it.
WHY
Unusual code frequently has a reason nobody wrote down.
WHAT TO RECORD
What you learn, as you learn it.
WHAT TO START WITH
Something small and self-contained.
WHAT TO AVOID
Restructuring before understanding Assuming code is wrong because it is unfamiliar