A practical guide: how to choose the best digital marketing agency?

Author : Mia El Jamali

Digital marketing agencies implement businesses’ digital strategies by managing their advertising campaigns. Historically, they rely on three pillars: SEO, which refers to organic search ranking on Google; SEA, which maximises website visibility through sponsored links; and Social Ads, which correspond to campaigns on social media platforms (Meta, TikTok).

However, the advent of generative Artificial Intelligence brings about a profound shift in marketing. It is no longer enough to optimise business visibility through traditional channels. Brands must now be directly recommended by LLMs (ChatGPT, Gemini, Claude) when users seek their advice. This is the GEO (Generative Engine Optimisation) revolution. Building on the foundations of SEO, GEO deploys new semantic strategies to ensure a company is cited as a reference by these AIs.

A brand’s reputation and profitability depend on its ability to assert itself across all these digital channels. This visibility is essential for building brand awareness and converting prospects who have not yet made a purchase. In this complex ecosystem, it is vital to surround yourself with experts. Choosing the best digital marketing agency is a major business challenge, a strategic decision that requires asking the right questions before committing.

1. Define your performance objectives

Before exploring market offerings, it is crucial to identify your company’s needs and the associated performance objectives. The concept of performance objectives operates on two major levels of business activity—spanning from the short to the long term—and must be closely tied to your business model as well as the competitive pressure you face:

• Sales objectives: Determine to what extent you want to increase your sales, assess your sales capacity, and define the scale at which the agency should acquire new buyers for you. In the short term, set the expected revenue growth resulting from this marketing investment.
• Profitability objectives: How much are you willing to invest to boost your sales while guaranteeing a positive margin? This entails precisely setting your target Customer Acquisition Cost (CPA) or your minimum Return on Ad Spend (ROAS).

Conducting this objective analysis will allow you to automatically rule out agencies pitching unsuitable solutions, ensuring you choose the partner best aligned with your financial ambitions.

2. Understand the role and complementarity of each marketing channel

Beyond the financial aspect, your business model and competitive pressure determine how you will combine your digital marketing channels. SEO-GEO, SEA, and Social Ads have highly distinct roles but remain deeply complementary:

• SEA: This is the go-to solution when your goal is to move inventory quickly and maximize immediate revenue by capturing existing, direct purchase intent.
• SEO and GEO: These are suited for building long-term brand awareness and authority. This lever requires giving it time to reach the top of Google rankings and to be cited by Artificial Intelligences, ultimately providing a steady stream of traffic.
• Social Ads: This allows you to reach an audience that wasn’t actively looking for you, positioning your brand at every stage of the customer journey on social media platforms (brand discovery, consideration, and retargeting website visitors).

Understanding the precise role and complementarity of each channel allows you to target agencies capable of making them work in synergy. This will prevent you from falling into the trap of providers who might sell you a single solution out of convenience, playing on a superficial understanding of these levers.

3. The trade-off between a full-service agency and a specialist approach

Next, you need to identify the agencies that are experts in the channels you want to activate. The question then arises of whether to define your marketing strategy by adopting a comprehensive approach or a segmented one. There are pros and cons to each of these choices:

• The segmented approach involves choosing a single marketing channel to address a very specific need (and therefore hiring a single specialized agency), or activating all channels but with separate agencies, each an expert in its respective field.
• The comprehensive approach, on the other hand, consists of trusting a centralised, full-service agency capable of managing all marketing channels simultaneously.

The segmented approach: overspecialisation

• The major advantage: Choosing a specialised agency for each type of channel ensures the expertise of the organisation and its specialists. Furthermore, it offers greater flexibility, allowing you to let go of one agency or another at any time without simultaneously losing all your marketing channels.
• The main risk: If you choose to activate multiple marketing channels at the same time, you will be forced to manage different agencies, orchestrate communication between them, and maintain a centralised view of several ongoing projects. This multiplies the supervision and coordination workload, along with the associated costs. At the same time, compartmentalisation between agencies risks hindering performance due to data silos. If your specialised SEO and SEA agencies do not communicate, you expose yourself to severe cannibalisation—for instance, if the SEA agency invests heavily in keywords for which your SEO pages are already ranking well organically.

The comprehensive approach: the Full Funnel model

• The major advantage: An agency managing the entire strategy can be a highly effective investment as it covers all stages of the conversion funnel. The complementarity of SEO, SEA, and Social Ads unfolds throughout the entire customer journey. At the top and middle of the funnel, SEO builds brand awareness while Social Ads stimulate desire and retarget prospects. At the bottom of the funnel, synergy is key: SEA secures immediate purchase intent, while SEO takes over for brand-specific queries, ensuring that users looking for you actually find you, thus generating leads and conversions. This approach also saves you time by providing a single point of contact and cross-channel reporting.
• The main risk: Entrusting your SEO-GEO, SEA, and Social Ads strategy to a single agency simultaneously carries a twofold risk. First, some organisations tend to overestimate their capabilities: ensuring the agency possesses proven, in-depth expertise in each of these channels is essential, as this is a non-negotiable condition for implementing a fully successful strategy. Second, this choice creates heavy reliance on a single provider. If the partnership isn’t a good fit, you will be forced to start your search all over again from scratch.

The ESV Digital approach : At ESV, we take a hybrid view of this trade-off. Instead of choosing between a comprehensive or segmented approach, we offer our clients the ability to create genuine synergy across marketing campaigns by reinforcing our SEO strategies with SEA or Social Ads, and vice versa, without ever compromising on quality. Our goal is to support you from A to Z while guaranteeing the expertise of our teams, who are seasoned specialists in their respective fields. We have put an end to silos: our experts communicate and share data in real time (e.g., high-converting SEA keywords immediately feed into SEO content) to maximise your brand awareness, visibility, and profitability, ensuring a holistic approach that never cuts corners on expertise.

4. A necessary understanding of Artificial Intelligence challenges

With the emergence of generative Artificial Intelligence, SEO is no longer enough for a brand to build awareness. Indeed, prospects today are highly tempted to ask LLMs for advice before simply conducting a Google search. For the future of your brand, it is therefore paramount that the digital marketing agency you choose has an in-depth knowledge of this technology, which holds strong prescriptive power, and remains at the forefront of innovation.

GEO is built on the foundations of SEO but is structured differently. Ensuring that the selected agency is well-versed in these 4 major areas is an excellent indicator of its technical maturity:

• The language of AI: the agency must implement technical markup on your site (Schema.org structured data) so that the AI unambiguously understands the nature and context of your content (author, product type, date). The more explicit the data is made for the algorithm, the more easily it can be reused.
• Ready-to-use answers: LLMs favor content that is understandable out of context. The agency must adopt a writing style using short, factually precise, and well-sourced blocks (figures, clear definitions) that carry authority in the eyes of LLMs.
• Comprehensive expertise: content that covers all facets of a topic (definition, examples, alternatives, use cases, limitations) is much more likely to be leveraged by an AI than partial content. The agency must create exhaustive Topic Clusters.
• Web authority: generative models rely on the overall reputation of the brand within their training sources. The agency must ensure you are mentioned in specialised press or expert forums in your industry, as these signals directly influence a brand’s presence in AI responses.

Mastering these four cornerstones is what now separates an agency applying yesterday’s methods from a partner capable of future-proofing your visibility on the web of tomorrow.

5. Verify the agency’s compatibility with your needs

Choosing an agency means choosing a partner who will support your company’s growth. Ensuring their expertise aligns with who you are—and therefore with your needs—guarantees they won’t simply apply cookie-cutter methods or generic strategies previously used on vastly different businesses.

Reviewing the agency’s client base upfront (their track record) gives you a sense of the industries whose challenges they truly understand. You should also look at the size of the companies in their portfolio to see if they share common characteristics with your own market expectations. Beyond the numbers, don’t hesitate to assess cultural fit: a good agency must adapt to your pace, your level of digital maturity, and your day-to-day communication style. Finally, the longevity of their client relationships is often the best indicator of a reliable partner capable of driving long-term value.

The ESV Digital approach : in keeping with this commitment to transparency, we provide in-depth case studies. They illustrate the diversity of our clients (B2B, Retail, E-commerce) and the tangible value we deliver to them. On our website, you will also find testimonials from the companies we support, allowing you to gather objective, real-world feedback on what it is like to collaborate with us on a daily basis.

6. Choose a pricing model that suits you

It is important to ensure that the budget you wish to allocate to your digital marketing agency matches what is being offered. Your budget should depend on the scale of the project you want to undertake, as well as your cash flow capacity. A digital marketing agency is a powerful growth lever, provided your business model allows you to generate a return on this investment.

Various billing models exist on the market: a monthly retainer (ideal for long-term building), a percentage of media spend, or even hybrid models. The most important thing is that the chosen compensation structure is fully aligned with your business objectives.

The ESV Digital approach : We are able to offer the most suitable pricing based on your specific context and maturity, whether that entails a monthly retainer, a hybrid model (consisting of a fixed base and a variable component), or a percentage of ad spend. Our goal is to build a win-win partnership where our financial interests are perfectly aligned with your success and profitability.

We hope we’ve shed some light on the pitfalls to avoid and the criteria to look for. To turn your digital marketing into a truly profitable investment with an expert partner: Don’t hesitate to Contact us to discuss your goals!