Write down one complete manual run: what arrives, what you change, how you check it, and where the result goes. Identify steps that are rule-based and repeat often; keep ambiguous decisions as a review step.
Build the smallest version in Workflows using synthetic input. Define the expected output for a normal item, an empty item, and a malformed item. Then test a repeated run to see whether it creates duplicates or overwrites good data. Make errors visible and keep a way to stop before external actions such as sending or publishing.
Automate the reliable middle of the task first, not every judgment at once.
Akousa