The routine
- Date range: last 30 days, or long enough to have real data.
- Sort by cost, descending. Ignore impressions entirely.
- Work down the list asking one question: would I have chosen to pay for this search?
- Every "no" becomes a negative, at phrase or exact match.
- Every surprising "yes" becomes a keyword in its own right.
What you are looking for
Research intent, free and cheap modifiers, adjacent products you do not sell, competitor and marketplace names, and job-seeker traffic.
Why weekly
Search behaviour drifts, new products change what you match, and Google's matching loosens over time. Set once and forget means it decays. More on negatives.