1. Define data models using types, interfaces, and schemas.
2. Define function signatures with input/output types.
3. Implement logic to satisfy the defined types.
4. Validate data at system boundaries using runtime checks.
5. Use discriminated unions for mutually exclusive states.
6. Apply functional programming patterns (map, filter, reduce).
7. Handle edge cases explicitly (empty arrays, null inputs).
8. Configure and use Zod for runtime validation.