Before Google can show your ad to anyone, it needs to know what you're selling — and keyword research is how you tell it. Think of keywords as the bridge between what your customers type into Google and the products or services you offer. Get this right, and your ads appear in front of the right people. Get it wrong, and you'll burn your budget on clicks that never convert.
This guide covers how to approach keyword research properly, what tools to use, and the common mistakes that trip up new advertisers every day.
Google Search campaigns work on an auction model — every time someone searches, Google runs a real-time auction to decide which ads appear and in what order. Your keywords determine when you enter that auction. If you're not bidding on the right terms, you're either invisible to the people most likely to buy, or you're showing up for searches that have nothing to do with your business.
Good keyword research tells you:
A seed keyword is a broad starting point — typically two or three words that describe your core product or service. If you run a plumbing business in Melbourne, your seeds might be "plumber Melbourne", "hot water system", or "blocked drain".
From those seeds, you build outward. Think about:
You don't need to guess. There are solid tools that show you actual search data:
Available inside Google Ads, Keyword Planner shows you search volumes, competition levels, and suggested bid ranges. It's the most accurate because it pulls from Google's own data. Note that it shows ranges rather than exact numbers unless you have active spend in your account.
If you have a website with some traffic, Search Console shows you what people are already searching to find your site organically. These are often your best-performing ad keywords too — they're proven search queries from real users.
Type a seed keyword into Google and watch the suggestions that appear. These are real searches people are making, ordered by popularity. Scroll to the bottom of the results page and you'll also see a "Related searches" section — another goldmine of keyword ideas.
Tip: Don't overlook what your competitors rank for. If a competitor's website appears for certain terms, those terms likely have purchase intent worth testing in your own campaigns.
In Google Ads, you don't just add keywords — you also choose a match type that controls how closely a search must match your keyword before your ad is eligible. Think of it as a filter dial that goes from "very specific" to "quite broad".
Your ad only shows for searches that match your keyword closely — same meaning, minimal variation. If your keyword is [plumber Melbourne], it might show for "Melbourne plumber" but not "plumber Sydney". Best for high-intent, well-understood terms where you know exactly what you're targeting.
Your ad shows for searches that include the meaning of your keyword. "plumber Melbourne" could trigger for "best plumber in Melbourne" or "affordable plumber Melbourne CBD". Good for capturing variations without going too broad.
The widest setting. Google uses AI to decide what searches are relevant to your keyword, sometimes quite liberally. It's powerful when paired with Smart Bidding (Google uses conversion signals to find relevant traffic), but risky without it — you can end up paying for completely unrelated clicks. Always use broad match with conversion-based bidding strategies and review your search terms report regularly.
How you organise your keywords matters as much as which keywords you choose. The basic structure is:
Keep ad groups tightly themed. If your ad group for "hot water repairs" also contains keywords about "blocked drains", you can't write an ad that speaks to both. Tight themes mean better ad relevance, which lowers your costs and improves performance.
A good starting point is 5–15 keywords per ad group, all closely related. If you have very different search intents, split them into separate ad groups.
Negative keywords tell Google when not to show your ad. This is just as important as the keywords you do target — it keeps your budget focused on relevant searches only.
If you sell premium handmade furniture, you probably don't want your ads showing for "cheap furniture" or "IKEA". Adding these as negatives saves you from paying for clicks that will never convert.
Common categories of negative keywords to consider:
High search volume is tempting, but it's not everything. A keyword searched 10,000 times a month that attracts window-shoppers is worth less than a keyword searched 200 times a month by people ready to buy.
As a rule of thumb, the more specific the search, the higher the purchase intent. "Buy ergonomic office chair Sydney" is from someone much further down the buying journey than "what is an ergonomic chair".
Key insight: Long-tail keywords (more specific, longer phrases) typically have lower search volumes but higher conversion rates. A good keyword strategy targets a mix of both.
Keyword research isn't a one-time task. Once your campaign is running, your actual search term data (visible in the Search Terms report inside Google Ads) will show you exactly what people typed before clicking your ad. This is invaluable.
Review it regularly and:
Since 2020, Google has reduced how much search term data it shares, so you won't see every click. But you'll still see enough to meaningfully improve your campaigns over time.
Google Ads Help: About keyword matching · Google Keyword Planner · Google Search Console
Common questions about this topic.
Keyword research for Google Ads is the process of identifying the specific search terms your target customers use when looking for your product or service, then organising those terms into a structured list for your campaigns. Unlike SEO keyword research (focused on organic ranking), Google Ads keyword research also considers search volume, cost-per-click estimates, competition level, and user intent (are they browsing, comparing, or ready to buy). The goal is to find high-intent terms worth bidding on at a profitable CPC.
The primary tool is Google Keyword Planner (free, built into Google Ads) — it shows search volume ranges, competition levels, and suggested bid ranges for any keyword. Supplement this with Google Search Console (shows actual queries driving organic traffic to your site), Google Ads Search Term Reports (real queries that triggered your ads), and third-party tools like Semrush or Ahrefs for competitor keyword analysis. The combination of all four gives a more complete picture than any single tool alone.
Negative keywords are queries you want to exclude from triggering your ads. Identify them by: reviewing your existing search term report for irrelevant queries, thinking through mismatched intents (e.g., if you sell premium software, exclude 'free'), listing competitor brand names you don't want to appear for, and considering geographic terms outside your service area. Build a negative keyword list before launching a new campaign, not just reactively after wasting spend.
A well-structured ad group typically contains 5–15 closely related keywords. Tightly themed ad groups — where all keywords share the same core intent — allow you to write more relevant ad copy and direct users to a more targeted landing page. Avoid ad groups with 50+ loosely related keywords; this dilutes relevance, hurts Quality Score, and makes it impossible to write ad copy that matches every keyword well. If you have many keywords, split them into multiple themed ad groups.
Search intent is the underlying goal behind a query. The four main intent types are: informational ('how does Google Ads work'), navigational ('Google Ads login'), commercial investigation ('best Google Ads agency'), and transactional ('hire Google Ads specialist'). For Google Ads, transactional and commercial investigation keywords typically convert best because users are closer to a purchase decision. Informational keywords often generate high click volume but low conversion rates — avoid them unless your campaign goal is brand awareness.
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