SEA (Search Engine Advertising)

How SEA works

SEA runs on a real-time auction system. When someone types a query into Google, an algorithm decides within milliseconds which ads to show, in what order and at what price. You set a daily budget and a maximum cost per click (max CPC), and Google shows your ads until your budget runs out.

The Quality Score (a quality rating from 1 to 10) is a decisive factor. It takes into account how relevant your ad is to the keyword, the quality of your landing page and the expected click-through rate. A high Quality Score (7+) lets you pay less while winning better positions. That is why landing page optimisation cannot be separated from a sound SEA strategy.

The ad formats available

Google Ads offers several formats depending on your goals. Search ads (text) appear in the search results and target active buying intent. Display ads (visual banners) reach people across the 2 million sites in Google's Display Network. Shopping ads show your products with a photo and a price directly in Google. YouTube ads (video) capture attention with visually engaging content. Finally, Performance Max campaigns use Google's AI to run across every channel at once.

The key SEA metrics

To steer an SEA campaign you need to watch several indicators. The average CPC (cost per click) ranges from €0.50 in less competitive sectors to €15 and more in insurance or legal services. The average CTR (click-through rate) on Search is 3.17%: a CTR below 2% points to a problem with the ad or the targeting. The average conversion rate on Search is 3.75%. The CPA (cost per acquisition) is the metric that matters most: what each lead or sale actually costs you.

SEA vs SEO: complementary, not opposed

SEA delivers results from day one, while SEO takes 3 to 6 months. The best strategy combines the two: SEA for quick wins and launches, SEO to build lasting traffic and reduce your dependence on paid campaigns. SEA data, meaning the keywords that convert best, also feeds your SEO strategy.

The costly mistakes in SEA

Without expertise, SEA can burn through your budget fast. The most common mistakes are: not using negative keywords, so you pay for irrelevant clicks, sending traffic to your home page instead of a dedicated landing page, failing to set up conversion tracking, and relying only on automated bidding with no strategy. A poorly optimised campaign can waste 30 to 60% of the budget.

Understanding keyword match types

One of the most underrated levers in SEA is the match type, which decides which queries trigger your ads. Broad match reaches the widest set of related queries, but with a high risk of waste. Phrase match requires your phrase to appear in order. Exact match triggers the ad only on very close queries, which gives you the best control. Good practice is to start with phrase and exact match to keep the budget under control, then widen gradually once you know which terms convert. A tradesperson targeting "plumber Rueil-Malmaison" on exact match avoids paying for "plumber salary" or "plumbing course".

A worked example of profitability

Nothing beats a concrete calculation to see whether a campaign pays. Picture a locksmith investing €1,490 a month in Google Ads. With an average CPC of €4, he gets 200 clicks. His landing page converts at 8%, which is 16 call-out requests. He wins half of them, so 8 jobs, at an average value of €220, generating €1,760 in revenue for €1,490 spent. His ROAS (return on ad spend) is 2.2x and his CPA is €50 for a customer worth €220. Running this calculation every month is what lets you adjust bids and cut the keywords that do not pay.

Remarketing: winning back visitors who left

On average, 96 to 98% of visitors leave a site without converting on their first visit. Remarketing (or retargeting) means showing your ads again to people who have already visited your site, on the Display Network, on YouTube or in their later searches. It is one of the most profitable levers in SEA because you are targeting prospects who are already interested, usually with lower CPCs and conversion rates 2 to 3 times higher than cold acquisition. For a small business, a modest remarketing campaign at €150 a month is often enough to recover leads that would otherwise be lost.

SEA best practice in 2026

To get the most from your campaigns this year, a few habits make the difference. Use audience signals to point Google's AI towards your best customers rather than leaving it to guess. Write at least 10 headlines and 4 descriptions per responsive ad so the algorithm can test combinations. Watch your lost impression share to see whether your budget is capping your visibility. Finally, align the message in the ad with the message on the landing page rigorously: that consistency lifts your Quality Score and mechanically lowers your CPC.

Local SEA for tradespeople and high street businesses

For a business serving its own area, local SEA is often the most profitable lever. Location ads show your address, your phone number and a click-to-call button in mobile results. Pairing those ads with your Google Business Profile lets you appear in both the map pack and the sponsored links. Tight geographic targeting, a radius of 10 to 20 kilometres around your service area, avoids spending on clicks from outside it. A concrete example: a mobile car mechanic who limits his ads to his town and the neighbouring areas, with call extensions switched on, picks up urgent enquiries at the exact moment the customer needs help, often with a conversion rate above 10%.

At ConvertiLab, we run your Google Ads and Meta Ads campaigns with transparent monthly reporting and continuous optimisation to maximise your return on investment.