An SEO agency improves how easily the right customers can find a business through search. In practice, that means much more than adding keywords to pages. A competent agency should investigate technical problems, understand search intent, improve important pages, strengthen local visibility where relevant, measure performance and explain what is being done in plain English.
The exact work should depend on the business. A local plumber, ecommerce store and national B2B company should not receive the same SEO plan.
What does an SEO agency actually do?
- Researches how potential customers search
- Audits technical SEO problems
- Improves service, product and landing pages
- Strengthens internal linking and site structure
- Works on local SEO and Google Business Profile where relevant
- Plans useful content around real customer questions
- Monitors rankings, traffic and conversions
- Identifies opportunities and problems over time
1. Understand the business before touching the website
Good SEO starts with the commercial objective. The agency should understand what you sell, which services matter most, which locations you serve, who your best customers are and what an enquiry or sale is worth.
Without that context, it is easy to chase high-volume keywords that bring traffic but no business.
2. Research search intent and keywords
Keyword research is not simply collecting phrases with search volume. The important question is what the searcher is trying to achieve.
A query such as “how does local SEO work” is informational. “SEO company Croydon” is much more commercial. Those searches need different pages.
An agency should group related searches by intent and decide whether the best destination is a service page, location page, product page or useful guide.
3. Audit the technical foundations
Technical SEO checks whether search engines can access, understand and index the website properly.
Common areas include:
- indexing and crawlability
- canonical tags
- redirects and broken links
- site structure and internal links
- mobile usability
- Core Web Vitals and performance
- structured data where appropriate
- duplicate or thin content
Our technical SEO audit checklist explains these checks in more detail.
4. Improve pages that already matter
Many websites do not need hundreds of new articles. They need stronger versions of the pages that customers already use to decide whether to contact the business.
An SEO agency may improve headings, copy, trust signals, internal links, calls to action, metadata and content depth so the page better matches the searcher’s intent.
5. Build useful content
Content should answer real questions, support commercial pages and add something useful that generic summaries do not.
Google’s current guidance for generative AI search emphasises unique, valuable, non-commodity content rather than content created simply to fill a keyword plan.
That means useful experience, original examples, practical explanations and first-hand insight matter more than publishing volume for its own sake.
6. Strengthen local SEO
For local businesses, SEO often includes Google Business Profile, location relevance, reviews, service-area content and accurate business information.
Google says local results are mainly influenced by relevance, distance and prominence. A good local SEO strategy therefore combines the website with the real business entity behind it.
See our local SEO guide for the fundamentals.
7. Improve internal linking
Internal links help users move between related pages and help search engines discover and understand site structure.
Links should be contextual and descriptive. They should not be added simply to hit a quota.
8. Measure what actually matters
Rankings are useful, but they are not the final business outcome.
An agency should also look at relevant organic traffic, qualified enquiries, calls, sales, conversion rate and how important pages are performing.
Search Console impressions can show visibility, but impressions are not search volume and they do not automatically mean commercial success.
What should an SEO agency report?
Reports should explain what changed, why it mattered and what happened next.
Useful reporting can include:
- important ranking movements
- organic clicks and impressions
- local visibility
- technical issues fixed
- pages improved
- qualified leads or sales where tracking is available
- next priorities
A report full of charts with no explanation is not useful to most business owners.
What should an SEO agency not promise?
No responsible agency can guarantee a specific organic ranking, guaranteed AI mention or fixed return from Google Search.
Search results change, competitors react and Google controls its own ranking systems.
An agency can improve the conditions for visibility and conversion, but it cannot own Google’s results.
Does SEO still matter with AI search?
Yes. Google’s current guidance says the same foundational SEO practices remain relevant for AI Overviews and AI Mode, and there are no special technical requirements or secret AI schema needed.
Important content still needs to be crawlable, indexable, useful, well linked and available in textual form.
For more detail, see our guide to AI search visibility.
How long does SEO take?
There is no universal timeline. A technically healthy website with existing authority may respond faster than a new site in a competitive market.
Early improvements can appear quickly, but meaningful organic growth usually requires sustained work over time.
How to choose an SEO agency
- Ask what they will work on in the first 90 days.
- Ask how they choose priorities.
- Ask which outcomes they will measure.
- Ask who will actually do the work.
- Look for clear explanations rather than jargon.
- Avoid guaranteed-ranking promises.
- Make sure they understand your business model, not just your website.
Bottom line
A good SEO agency should make search marketing clearer, not more mysterious. Its job is to connect technical quality, useful content, local or commercial relevance and measurement so the right customers can find the business and take action.
If you need help with your own site, see Core Web UK’s SEO services.