Define the test scope and objectives
Identify the system under test
Break the system into major components
Break each component into subcomponents
Continue decomposing until testable units are reached
Map risks to each branch of the tree
Assign test cases to each leaf node
Prioritize branches by impact and likelihood of failure
Ensure coverage of normal, edge, and failure paths
Review the tree for missing branches
Trace each test case back to a requirement or risk
Update the tree as the system changes