How to Choose an Ecommerce Marketing Agency

Most agency selection processes compare the wrong things. Brands compare case studies, which are selected by the agency; pricing, which is not comparable across different scopes; and chemistry on a call, which measures the salesperson rather than the team.

The variables that actually predict whether an engagement works are fit, staffing, measurement, scope clarity and the agency’s willingness to say no. Below is how to judge fit first, then fourteen questions that surface the rest, the answers that should give you pause, and the checks you can run before you speak to anyone.

Start with fit, before anything else

Fit is the filter that saves you from most bad outcomes, and it has three parts: specialisation, category and stage.

Hire a specialist, not a generalist

Look at the agency’s client base. If it runs lead generation, ecommerce, retail and a little of everything else, it is doing a little of everything else on your account too. Ecommerce has its own operating rhythm, from feed quality and catalogue structure to creative refresh cadence and the relationship between acquisition and retention, and that rhythm is learned by doing it repeatedly and not by adapting a lead generation playbook. As a rule, an agency you hire as your ecommerce agency should have at least 70 percent of its clients in ecommerce. Ask for that number directly.

Look for real experience in your category

Every industry has its own techniques. Supplements carry compliance constraints and a subscription economy. Beauty lives on creative volume, shade and skin type merchandising, and heavy social proof. Apparel is a returns and size curve problem before it is an advertising problem. An agency that has run brands like yours already knows where the traps are, and you are not paying for that education a second time. Ask which brands in your category they have run, what the constraints were, and what they learned.

Look for a size and stage match

An agency that has scaled a nine figure brand has learned things that may not transfer to a brand doing two million a year, and the reverse is equally true. The question is not how big their biggest client is, it is whether they have taken a brand from where you are now to where you want to be next. Stage matters most at the start. Launching a brand from ground zero is the hardest work in this business, and it needs a specific kind of agency: one with genuine branding and creative strategy capability, and the team depth to move quickly, learn quickly and pivot when the first answer is wrong. If you are pre launch or early, screen for it hard.

Checks to run before you take a call

The fourteen questions

On staffing

• 1. Who is in my account daily, and what is their seniority? The concerning answer is any version of “our team handles it.” You want a name and a role. The gap between two agencies at the same price is usually here.
• 2. How many other accounts does that person carry? There is no universally correct number, and it varies enormously by channel and account complexity. What matters is that the agency knows the number and will say it. An agency that has not thought about workload per person is not managing it.
• 3. Who is on the call today, and will they be on the account? Ask it plainly. Senior people selling and junior people delivering is a legitimate model when it is disclosed and the senior person stays involved. It is a problem when it is concealed. Ask to meet the account lead and the people who will execute the key functions before you sign.

On measurement

• 4. What metric will we hold you to, and who calculates it? The concerning answer is platform reported ROAS alone. Platform numbers are self reported by the party being evaluated. A serious agency will want a blended measure reconciled against the store’s own revenue, and will tell you which number is the source of truth before the engagement starts rather than after a disappointing month.
• 5. How will you handle attribution disagreements? There will be disagreements. Every attribution model produces a different answer and none of them is objectively correct. What matters is that a tie breaking method is agreed in advance. Common approaches include holdout tests, geo splits and simple pre and post analysis on spend changes.
• 6. What does the reporting look like, and how often do we speak? Ask for a redacted sample of a real report, not a template. The difference is immediately visible.

On scope and the work itself

• 7. What exactly is included, and what triggers an additional cost? Get this in writing. The most common source of friction in agency relationships is not performance, it is a disagreement about whether something was in scope.
• 8. Who produces creative, and at what volume? If creative is not in scope, the programme depends on someone else supplying it at the required cadence. That dependency should be named and resourced before the contract is signed, because it is the most common reason paid social programmes stall.
• 9. Can I see the actual work? Ask to see real deliverables, not a highlights reel: static and video ad files, creative concepts, email designs, landing pages, reports. A good agency will happily open its files and walk you through several examples across different brands. You are judging craft and consistency, not the case study slide built around the one campaign that worked.

On commercial terms

• 10. Do we own the accounts, the data, the assets and the tools? The answer must be yes to all of it, without qualification. Every ad account, analytics property, pixel and CAPI setup, Klaviyo or other subscription, creative file and piece of content should be in your name, on your billing, with the agency granted access. Agencies that hold accounts “for convenience” hold you hostage. Confirm ownership in writing before anything is built.
• 11. What is the commitment, and how do I leave? Do not sign long lock ins. Ninety days is the most you should accept, and it should exist only so the work has time to show an effect. Agencies that require six or twelve month commitments are usually protecting themselves against their own retention rate. Evestar works month to month for exactly this reason: it keeps the pressure where it belongs, on us.

On judgment

• 12. Tell me about an engagement that did not work, and why. An agency that cannot name one is either very new or not being straight with you. Whether the agency can articulate its own contribution to the failure rather than the client’s is the single most informative response in the process.
• 13. What would you tell me not to do? A good answer arrives quickly and costs the agency something. If every idea you float is met with enthusiasm, you are speaking to a salesperson, not an operator.
• 14. What would make you conclude in ninety days that this is not working? An agency that has a specific answer has thought about failure and will recognise it early. An agency that has never considered the question will still be reporting optimistically in month five.

What to be sceptical of

• Guaranteed results. Nobody can guarantee a revenue number, a ROAS or a ranking position, because no agency controls the variables that decide them: your product, pricing, margins, inventory or operations. When an agency guarantees an outcome, it is either overselling or it does not understand its own job. What a good agency commits to is process, cadence, transparency and the standard of work.
• Guaranteed rankings or positions. The same logic applied to search. Any guarantee is either meaningless in the fine print or is being achieved on terms so uncompetitive that ranking there is worth nothing.
• Long lock in contracts. If the commercial terms are the strongest part of the pitch, ask why the work needs protecting.
• A timeline that sounds comfortable. Competitive commercial terms in established categories are contested by companies who are themselves professionals at competing for them. Anyone promising a fast result in a hard query space is either inexperienced or is describing an easier term than the one you asked about.
• Case studies with percentages and no baseline. A 400 percent increase from a small enough starting number is not evidence of anything. Ask for the absolute figures, or at least the starting point and the time period.
• A proposal that matches your request exactly. If an agency has diagnosed nothing and challenged nothing, it has not looked at your account, it has looked at your brief.

Frequently asked questions

Related reading: what an ecommerce marketing agency costs and why, how we run growth for ecommerce brands, and engagements with the starting numbers included.