How to Choose a Digital Marketing Agency
An Honest Guide for UK SMEs
Let’s start with something the digital marketing industry doesn’t like to admit: it is genuinely difficult to tell a good agency from a bad one, especially in the early months of a relationship. Digital marketing has a reputation as a dark art – and that reputation exists for a reason. Results can take time to materialise, the technical work happening behind the scenes is largely invisible to clients, and the metrics that matter are easy to obscure beneath those that merely look impressive.
This opacity is precisely what makes it so easy for businesses to pay significant fees month after month and never quite know whether they’re being served well or simply being strung along. According to LOCALiQ’s 2024 UK Digital Marketing Survey, around a third of UK marketing professionals are dissatisfied with their digital marketing performance. In our experience working with UK SMEs, a significant proportion of that dissatisfaction isn’t a marketing problem – it’s an agency problem.
This guide is written from the perspective of an agency that has spent years cleaning up after bad ones. We’ll tell you what to look for, what to run from, and how to evaluate whether an agency is actually delivering – before you’ve signed anything. If you want to understand more about how a well-run digital marketing service should work, we cover that throughout.
Why Digital Marketing Is So Hard to Evaluate
Why do so many businesses end up stuck with a bad agency?
The fundamental problem is information asymmetry. An experienced digital marketing professional can assess an agency’s work within minutes – looking at technical SEO foundations, ad account structure, content quality, conversion tracking setup, and the coherence between a client’s website and their marketing activity. A business owner without that background genuinely cannot make the same assessment. This isn’t a criticism – it’s simply the nature of a specialised discipline.
The industry has historically exploited this gap. Long-term contracts lock clients in before results have materialised. Vanity metrics – impressions, follower counts, website visits – are presented in glossy monthly reports in place of the numbers that actually matter: leads, cost per lead, and revenue. SEO is a particularly easy discipline to hide behind, because anyone can truthfully say that results take six to twelve months while doing very little of substance.
The average UK agency client relationship lasts around eleven to eighteen months. That’s not because digital marketing stops working after a year – it’s because most clients eventually reach a breaking point and leave. Greyturtle’s average client relationship runs to over four years. The difference isn’t luck; it’s the result of being transparent about what’s happening and delivering results that make leaving feel unnecessary.
The Red Flags: What to Watch For
What are the warning signs of a bad digital marketing agency?
Junior teams with limited real-world experience
This is the most common structural problem in the agency industry. It’s financially efficient to hire graduates, train them quickly, and deploy them on client accounts while charging senior rates. The client never meets the actual experts who pitched the work – they’re managed by someone who may have been in digital marketing for eighteen months and has never worked in-house at a business facing real commercial pressures.
Before engaging any agency, look up the people who would actually work on your account on LinkedIn. Check their employment history. Have they spent time in senior roles in industry, or have they gone straight from university into agency work? There’s nothing wrong with being early in a career – but there’s a significant difference between someone who genuinely understands B2B buying cycles, conversion optimisation, and budget management from experience, and someone who is learning those things on your account.
Unwillingness to connect you with existing clients
A confident agency with genuinely satisfied clients should be happy to facilitate introductions. If an agency hedges, cites client confidentiality as a blanket reason to avoid this entirely, or only offers written testimonials without the option of a real conversation, that tells you something. The agencies most willing to put clients in front of prospects are the ones who know what those conversations will reveal.
Ask to speak to two or three clients in situations similar to yours. If the agency is doing good work, those conversations will confirm it. If they’re reluctant to arrange them, ask yourself why.
No measurable results from paid advertising
SEO takes time – typically three to six months before meaningful organic ranking improvements appear, and longer to build significant lead volume. This is a genuine reality of the channel and not in itself a cause for concern in the early months. Paid advertising is different. A well-configured Google Ads campaign should begin generating enquiries or sales relatively quickly – within days or weeks of going live, not months.
If an agency has been running your paid ads for three months and cannot show you a clear cost per lead or cost per sale, something is wrong. Either the campaign isn’t generating results, or the reporting isn’t transparent enough to reveal whether it is or isn’t. Both are problems.
Running paid ads without addressing the website
This is a specific but extremely common mistake that costs clients significant money. An agency that launches paid advertising campaigns while leaving a client’s existing website unchanged is sending traffic to a site that may be slow, poorly structured, difficult to navigate on mobile, or simply unconvincing. No amount of well-targeted ad spend will compensate for a website that doesn’t convert.
Before paid ads go live, the website – and specifically the landing pages those ads direct to – should be reviewed and improved where necessary. If an agency proposes to run ads without mentioning the website, ask explicitly what they plan to do to ensure the site can convert the traffic they’re about to send it.
Long-term contracts and opaque pricing
A confident agency doesn’t need to lock clients into twelve-month minimum contracts. Long contracts are a risk management tool for agencies, not a service benefit for clients. They make it expensive and administratively difficult to leave even when the relationship isn’t working.
Similarly, an agency that won’t give you a clear, written breakdown of what they charge and what that includes before you’ve committed to working with them is setting expectations for how transparent the relationship will be. According to research by HubSpot, pricing transparency is one of the most significant factors in B2B purchasing decisions – and yet a surprising number of agencies treat it as a negotiating advantage rather than a baseline commitment to clients.
Greyturtle publishes its pricing openly on our website and operates on month-to-month contracts with thirty days’ notice. This isn’t just a marketing position – it’s the structure we’d want as a client, and it means our clients stay because the work is delivering, not because leaving is difficult.
What to Actually Look For
What are the signs of a good digital marketing agency?
Seniority and real-world experience in the team
The best agencies have senior people doing the work, not just pitching it. Look for team members who have held senior in-house marketing roles, who understand business dynamics beyond the digital marketing dashboard, and who can talk credibly about commercial outcomes rather than channel metrics.
A clear approach to measurement from day one
A good agency should tell you, before the work starts, what they will measure, how they will report it, and what success looks like at three months, six months, and twelve months. If an agency can’t answer those questions clearly at the outset, they won’t be able to answer them clearly once the relationship is underway.
Case studies with real outcomes
Look at an agency’s case studies carefully. The strongest ones describe a specific client challenge, explain what was done, and show a measurable outcome – not percentages that don’t tell you what they’re percentages of, but directional outcomes that are plausible and specific. Greyturtle’s case studies cover clients including a mobility ecommerce business whose monthly revenue tripled following a product data and PPC overhaul, and a heating business whose Performance Max campaigns generate high inbound call volume at very low cost per call. These are the kinds of specific, verifiable outcomes that distinguish a well-run agency from one that generates impressive-sounding statistics.
Look at the agency’s client websites
If you can identify businesses that the agency works with – from their client page, case studies, or testimonials – visit those websites. Are they fast? Do they look professional? Are they easy to navigate on mobile? Do they have clear calls to action? You may not have a specialist’s eye for technical SEO or conversion rate optimisation, but you can form a genuine impression of whether those sites look like they’re being well maintained. If the agency’s own website and its clients’ websites are slow, poorly designed, or unconvincing, that tells you something important.
Referral-driven reputation
Ask how most of the agency’s new clients find them. An agency whose growth is predominantly driven by client referrals is one whose existing clients are satisfied enough to recommend them – which is the strongest form of social proof available. The majority of Greyturtle’s new business comes from existing client referrals. We could spend that budget on advertising ourselves, but we’d rather earn new clients the same way we earn the trust of existing ones.
How to Measure Whether Your Agency Is Doing a Good Job
What metrics should you use to evaluate your digital marketing agency?
For SEO: The primary metrics are keyword rankings for your target search terms and organic search traffic to your website. Both are tracked through Google Search Console, which any competent SEO agency will have set up and should be sharing data from regularly. Bear in mind that meaningful ranking improvements typically take three to six months from the start of active work, and that you should be seeing a clear upward trend by month four or five. Enquiries from organic search is the ultimate measure, but rankings and traffic are the leading indicators.
For PPC: Two metrics matter more than any other for most SMEs: cost per lead and ROAS.
Cost per lead is exactly what it sounds like – the total amount spent on advertising divided by the number of leads generated. What’s acceptable varies significantly by sector and deal value: a business where a single client is worth £20,000 can sustain a much higher cost per lead than one where a sale is worth £200. A good agency will help you establish what a lead is worth to your business before setting performance expectations.
ROAS – Return on Ad Spend – is the relevant metric for ecommerce businesses. It measures how much revenue is generated for every pound spent on advertising. A ROAS of 3 means every £1 of ad spend generates £3 in revenue. A ROAS of 10 means every £1 generates £10. Greyturtle regularly achieves ROAS between 10 and 20 for ecommerce clients – figures that are exceptional by industry standards and that are only possible when campaigns are tightly structured, product data is properly optimised, and landing pages are built to convert. If your agency is delivering a ROAS of 2 or 3 and hasn’t explained why that’s acceptable given your margins, it’s worth asking the question.
The report you should be getting: Monthly reporting from a good agency should show you the metrics that matter for your specific channels, in plain language, with a clear narrative about what changed, why, and what will be done differently or additionally as a result. A report that shows you a lot of numbers without explaining what they mean, or that emphasises metrics you can’t connect to your commercial results, is a report designed to look impressive rather than to inform you.
Questions to Ask Before Signing
What should I ask a digital marketing agency before committing to work with them?
Who will actually work on my account, and can I see their LinkedIn profile? The people in the pitch room are not always the people doing the work. Ask specifically who would handle your SEO, your PPC, or whichever services you’re engaging. Look them up. Check how long they’ve been in the industry and what they did before joining the agency.
Can you connect me with two or three clients in a similar situation to mine? If the answer is yes and they facilitate it easily, that’s a strong signal. If the answer is evasive, take note.
What will you measure, and how will you report it? A clear, specific answer to this question before the engagement starts is a good indicator of how accountable the agency will hold itself during the engagement.
What will you do to prepare our website before running paid advertising? If paid ads are part of the scope, this is non-negotiable. An agency that plans to start spending your ad budget without addressing the site it’s sending traffic to isn’t managing your interests properly.
What are your contract terms, and what happens if I want to leave? A straightforward, honest answer – “month-to-month, thirty days’ notice, no penalties” – is what you should be looking for. Anything more complicated than that deserves scrutiny.
What does your pricing include, and what isn’t included? Get this in writing before you sign anything. Surprise costs – for content creation, for additional reporting, for platform fees – are a common source of dissatisfaction in agency relationships.
A Note on Client Budget and Realistic Expectations
Can I get good digital marketing results on a small budget?
Yes, but the realistic expectations change significantly depending on budget. An agency working with a client on a minimum retainer will do less than an agency working with the same client on a larger one – and a good agency will be transparent about this distinction rather than overpromising what a smaller budget can achieve.
Greyturtle’s minimum engagement is £700 per month. At that level, the focus is typically on the highest-impact activities for the specific situation – often local SEO for service businesses, or SEO foundations for B2B services – rather than a full multi-channel programme. We wouldn’t tell a client on a £700 retainer to expect the same output as one on a £2,000 retainer, because that wouldn’t be true.
What you should always be able to expect, regardless of budget, is transparency about what is being done, why, and what it’s delivering. If you’re not getting that, the problem isn’t the budget – it’s the agency.
Why Greyturtle Is Built the Way It Is
The structure of Greyturtle – senior-only team, transparent pricing, month-to-month contracts, direct access to the people doing the work – isn’t accidental. It’s the direct result of Catherine Hazeldine spending over two decades watching how the agency industry operates and deciding to build something that she’d want to work with as a client.
The average Greyturtle client stays for over four years. The industry average is eleven to eighteen months. We don’t think that gap exists because we’re uniquely talented; we think it exists because we tell clients what’s actually happening, we don’t lock them into contracts they can’t exit, and we charge fairly for genuinely senior work.
If you’re currently working with an agency and something doesn’t feel right – if the reporting feels opaque, if you’re not sure who’s actually doing the work, if results aren’t materialising and explanations feel vague – trust that instinct. It’s usually correct.
About the Author:
Catherine Hazeldine
How to Find the Right Agency for Your Business
Most businesses find their best agency relationships through referrals from trusted contacts who have worked with the agency and can speak to the experience honestly. If you don’t have that network, the next best approach is the one outlined in this guide: ask the right questions, look at the work, speak to existing clients, and pay close attention to how transparent the agency is about its pricing, its team, and what it can realistically deliver.
The agency you want is one that tells you the truth from the first conversation – including when the truth is that your budget won’t stretch to everything you’d like to do, or that your website needs work before paid ads can deliver the results you’re hoping for.