Negative keywords are the highest ROI optimisation in Google Ads that most advertisers underinvest in. Adding them costs nothing, takes a few hours, and the savings are permanent: every dollar not spent on irrelevant queries is a dollar available for queries that convert.
Here is the exact audit process we use with new clients.
Step 1: Pull the search terms report
In Google Ads, go to Keywords → Search Terms. Set the date range to the last 90 days (or since campaign start if less than 90 days). Download the full report to a spreadsheet.
Sort by spend descending. You want to see where most of your budget is going first.
Step 2: The five categories to always exclude
1. Competitor brand names (unless intentional)
If you are not running a deliberate competitor campaign, add competitor brand names as negatives. You are paying to show up for users who are already loyal to a competitor: conversion rates are low and CPCs are high.
2. Informational queries
Terms like "what is", "how does", "meaning of", "definition of", "history of" indicate research intent, not purchase intent. Unless you are specifically targeting top-of-funnel traffic, exclude them from conversion-focused campaigns.
3. Job-seeker queries
"Jobs", "career", "salary", "how to become", "internship", "CV", "resume". These are people looking for employment, not your product. Add all variations as negatives.
4. Free or DIY intent
"Free", "open source", "DIY", "template", "free trial" (if you do not offer one), "cheap", "low cost", depending on your positioning. If these do not match your offer, exclude them.
5. Location exclusions
If you do not serve certain locations, exclude them as negative keywords AND in campaign location settings. Relying only on location settings is not enough: users in your target location can search for "[service] + [city you do not serve]".
Step 3: Scan for irrelevant industry terms
Sort by impressions (high to low). Look for terms that are related to your industry but not your specific product. A B2B software company regularly gets triggered for consumer searches in the same category. A local plumber gets triggered for national DIY guides.
Step 4: Add as a negative keyword list
Do not add negatives individually to campaigns. Create a shared negative keyword list (Tools → Shared Library → Negative keyword lists) called "Master Exclusions". Apply it to all campaigns. Future additions to the list apply automatically.
Step 5: Set up a monthly review
The search terms report is always generating new data. Schedule a monthly 30-minute review to catch new irrelevant terms before they accumulate significant spend. Set a calendar reminder. This is the highest-ROI 30 minutes in your paid search month.
The result
For the client mentioned above, a single afternoon audit identified $4,100/month in spend on job-seeker queries (they offered "analyst" services, triggering "data analyst jobs"), competitor brand terms, and informational queries. After adding negatives, same budget delivered 34% more clicks to relevant queries and conversion rate improved 18% because the traffic quality was higher.