Negative keywords are the cheapest form of optimisation in Google Ads. They stop your account paying for searches that will never become customers, and the effect on a small budget is usually immediate. The problem is that they are a chore rather than a deliverable, so they get skipped until the account is quietly spending twice what it should.
Where the list comes from
Start from your own keyword list and your knowledge of the service. Anything that describes a different job, a different location, a different customer type or a different stage of buying is a candidate. Then read the search terms report weekly for the first month, and monthly after that. The report shows what people actually typed, which is rarely identical to what you assumed they would type.
A useful habit is a shared sheet with three columns: the search term, the decision, and the reason. The reason matters six months later, when someone asks why a profitable term was excluded.
Categories that most small accounts miss
Free, cheap, discount, wholesale and used are straightforward. DIY, how to make, and repair instructions catch people who intend to do the job themselves. Jobs, salary, career, internship, hiring and course catch job seekers and learners, who are researching rather than buying. Cheap flights and hotel bookings catch travel research. Terms about competitors are often expensive and only worth keeping if they convert. Location terms for cities you cannot serve are pure waste. Finally, brand terms of businesses that are not you catch people looking for someone else.
Add these as account-level negatives when you are confident, and as campaign-level negatives when you want to keep the term available elsewhere.
Where to apply the exclusions
The scope of a negative matters, and getting it wrong in either direction causes problems. An account-level exclusion applies everywhere, which suits terms that could never be relevant to any campaign, such as jobs or DIY instructions. A campaign-level exclusion applies to one campaign only, which suits a term you want to test in a brand campaign but never in a competitor campaign. An ad group-level exclusion is for a term you want to keep available elsewhere in the same campaign.
The practical warning is about over-exclusion. If you exclude a phrase at account level because it did not work in one campaign, you may remove it from a campaign where it would have converted. When in doubt, use the narrowest scope that solves the problem, and revisit it in a few weeks.
How to tell whether the list is doing its job
Two checks are worth adding to the monthly review. First, compare the share of spend that came from search terms you later excluded with the total spend. If that number is meaningful, the list is earning its place, and the next question is whether the same pattern is recurring from a different phrasing. Second, check whether the cost per enquiry has improved since the list was tightened, and note whether volume dropped at the same time. A lower cost with much lower volume is not automatically an improvement.
What a good list looks like in practice
A useful negative list for a Pune service business is short and specific rather than enormous. It might contain around fifty to a hundred entries in total, grouped into categories with a note for each. It is reviewed monthly, it grows when a new irrelevant pattern appears, and it is shared with whoever handles the account. If a provider shows you thousands of entries with no explanation, ask what proportion is actually doing work.
Review it on a schedule, not once
Set a recurring time, ideally once a month, and put it in the same slot as your monthly report. Look for three things: new irrelevant patterns, new expensive but unproductive terms, and terms that are converting so well they deserve a dedicated campaign. Removing a wasteful term is easier than chasing extra budget later.
Do not add a hundred words in one sitting based on a hunch. Add the confirmed pattern, watch the next few weeks, and check whether cost per enquiry improved.
Match types and negatives work together
Negative keywords are most valuable when you are using looser match types, because looser targeting brings in more unexpected searches. If you rely entirely on exact match, the negative list still matters, but it does less work. Decide your match type strategy and your negative list strategy together rather than separately, and record the reasoning in writing so it survives a change of account manager.
Questions to ask whoever manages the account
Ask how often the search terms report is reviewed and by whom. Ask for the current negative keyword count and the reasoning for the largest categories. Ask what proportion of spend came from search terms that were later excluded. Ask whether exclusions are applied at account, campaign or ad group level, and why. A provider who cannot produce that list within a day probably is not maintaining it.
Maintaining the list is part of the routine in our Google Ads management service, which starts at INR 12,000 per month, with ad spend billed separately by you to Google and any third-party platform subscriptions billed separately. More detail is in our Google Ads guides, and you can raise a specific account question through the contact page.
Common questions
What is the single best way to find wasted ad spend?
Read the search terms report rather than the keyword list. It shows the actual queries that triggered your ads, including the ones you never wrote. Group the obviously irrelevant phrases, add them as negatives, and repeat. On a small account this takes under an hour and typically recovers spend every month. Skipping it is the most common reason budgets shrink without anyone knowing why.
Should I add my competitors' names as negative keywords?
It depends on your decision, not on a rule. If you cannot outbid competitors profitably, adding them as negatives saves money. If competitor searches convert well for you, leaving them in may be worth the cost. Decide per campaign, and check the actual cost per enquiry from those terms before deciding. Competitor terms are often expensive, so measure rather than assume.
Will negative keywords hurt my reach?
They reduce reach only in the searches you exclude. Excluding a term that never produces a relevant enquiry does not cost you anything real. Excluding a term that quietly brings good customers does. That is why the search terms report should be reviewed on a schedule instead of adding dozens of words once. Add one confirmed pattern at a time and watch the effect.