London has thousands of marketing agencies, from one-person consultancies to global networks. Most of them can produce a polished pitch deck. Far fewer can explain, in plain English, how they will turn your budget into customers — and prove it month after month.
This guide is a practical checklist. It is written for owners and managers of small and medium-sized businesses who want to hire an agency for SEO, Google Ads, social media or a combination, and who want to avoid the most common and expensive mistakes.
Start with the outcome, not the service list
Before you contact a single agency, write down what success looks like in one sentence. For example:
- “Twenty more qualified enquiries a month for kitchen extensions in north London.”
- “Online sales growing month on month while keeping cost per order profitable.”
- “Sell out a 300-seat conference in London by a fixed date.”
That sentence becomes your filter. An agency that immediately talks about “brand awareness”, “engagement” or “impressions” without connecting them to your outcome is selling activity, not results.
It also helps you decide which channels matter. Local service businesses often win most from Google search, Google Maps and reviews. E-commerce brands tend to need Google Shopping, paid social and email. B2B companies may need search, LinkedIn and a website that converts high-value visitors. A good agency will challenge your assumptions here — but it should be anchored to your goal.
Know what you are buying
Digital marketing is an umbrella term. Make sure you and the agency mean the same thing:
| Service | What it should include | What it is not |
|---|---|---|
| SEO | Technical fixes, local SEO, content, on-page optimisation, link earning, reporting | A one-off “SEO package” with no ongoing work |
| Google Ads (PPC) | Account structure, keyword strategy, ads, landing pages, conversion tracking, weekly optimisation | Setting up campaigns and leaving them running |
| Paid social | Audience strategy, creative, testing, retargeting, reporting on leads and sales | Boosting posts |
| Content | Pages, articles, posts and emails with a clear purpose | Posting for the sake of posting |
| Web design | A fast, mobile-friendly site built to convert, with SEO foundations | A template with your logo on it |
| Automation & CRM | Lead capture, follow-up, integrations, pipelines | A tool subscription with no setup |
If a proposal lists services without explaining the work inside them, ask. “Monthly SEO” can mean anything from serious technical and content work to a single automated report.
Ownership: the non-negotiable
This is the single most important point in the whole guide. You should own your marketing assets. That means:
- Domain name registered in your name or your company’s name.
- Website and its content, with admin access for you.
- Google Ads, Meta and other ad accounts created under your business, with the agency added as a user or manager.
- Google Analytics, Google Search Console and Google Business Profile owned by your business account.
- Creative files — designs, videos, copy — handed over or accessible.
If an agency runs ads from its own account, you lose your data and history when you leave. Starting again from zero is expensive. A trustworthy agency will happily set everything up in your name.
Questions to ask every agency
Use the same questions with each shortlisted agency so you can compare like for like.
About experience
- Have you worked with businesses like mine — similar size, sector or customer?
- Can you show examples of work and explain what changed for that client?
- Who exactly will work on my account, and what is their experience?
About strategy
- Based on what you know so far, which channels would you prioritise and why?
- What would you not do for my business?
- What do you need from me to make this work?
The answer to question five is revealing. Agencies that say yes to everything rarely do any of it well.
About measurement
- Which numbers will you report on, and how often?
- How will you track enquiries, calls and sales — not just clicks?
- What does good look like after one month, three months and six months?
About the relationship
- How do we communicate, and how quickly do you respond?
- What is the notice period, and what happens to my accounts and data if I leave?
- How are fees structured, and is media spend kept separate?
Red flags
Be cautious if you hear or see any of the following:
- Guaranteed rankings or results. No one controls Google’s rankings or the ad auction. Honest agencies promise process and transparency, not positions.
- Ad accounts owned by the agency. See the ownership section above.
- Vague deliverables. “Ongoing optimisation” with no detail of what that means.
- Reporting on vanity metrics only. Impressions and followers without leads, sales or cost per customer.
- Long lock-in contracts before any results. A reasonable notice period is normal; a year-long commitment with no performance review is not.
- Hidden media mark-ups. You should see exactly what was spent on ads.
- No questions about your business. If they pitch before understanding your customers, margins and capacity, the plan is generic.
How to compare proposals
Once you have two or three written proposals, lay them side by side and compare:
- Scope: exactly what work is included each month.
- People: who does the work and how much of their time you get.
- Measurement: what is tracked, how it is reported and how often.
- Ownership: whose name the accounts and assets are in.
- Terms: notice period, minimum term and exit process.
- Price: the agency fee and the recommended media budget, shown separately.
The cheapest proposal is often the most expensive in the long run if it buys activity rather than outcomes. Equally, the most expensive is not automatically the best. Value is what you get for every pound, measured against the outcome you wrote down at the start.
Local knowledge matters in London
London is not one market. Search behaviour, competition and cost per click can differ widely between, say, Mayfair and Walthamstow. An agency that understands boroughs, postcodes and how Londoners search (“near me”, by area, by station) can target budget more precisely and write messaging that feels local.
That does not mean the agency has to sit in the same building. Most agency work — strategy calls, campaign management, reporting — happens remotely. What matters is that they respond quickly, explain clearly and understand your market.
What a good first 90 days looks like
A well-run engagement usually follows a pattern like this:
- Weeks 1–2: discovery and audit. Access to accounts, review of what exists, tracking checked or fixed, goals agreed.
- Weeks 2–4: foundations. Conversion tracking live, quick wins implemented, campaigns or content plan launched.
- Months 2–3: learn and improve. Data collected, underperformers cut, budget moved to what works, first proper monthly review against the agreed goals.
If after the first month you still do not know what has been done and why, that is a signal to ask harder questions.
How Hidook works
Hidook is a London-based digital marketing and web design agency. We work with businesses in London, across the UK and in Ireland. Our approach follows the principles in this guide: you own your accounts and data, fees are kept separate from media spend, and we report against agreed goals in plain English.
If you are comparing agencies, we are happy to be one of them. Book a free discovery call and ask us the twelve questions above.