The only service here where you spend twice: once on the work and once on the advertising itself. Confusing the two is the most common way to lose track of what it actually costs.
What you are actually buying
You are buying someone else’s time and judgement about where your advertising money goes. You are not buying the clicks; you pay for those separately, to Google or Meta.
That is why the first two questions are always the same: whose name the account is in, and how the fee is calculated. Everything else is easier to fix than those two.
What each budget realistically buys
A fee of 15 – 25% of spend
The most common model. Works at larger budgets. At a small budget it means the provider earns too little to spend real time.
Fixed 200 – 800 € / month
More predictable and more honest at small budgets, because the fee does not grow with spend. Ask how many hours sit behind the number.
Under 100 € / month
You are buying a few hours a month. Enough to keep an existing campaign running, not to build or rebuild one.
The first questions
P1
Whose name will the ad account be in?
Why you ask
The account holds the entire history of what worked. When you part ways it either comes with you or stays with them, and the next provider starts blind.
A good answer
The account is yours, they get partner access. This is standard practice and creates no inconvenience for a serious provider.
A bad answer
"We run it through our account, it is cheaper that way." Sometimes there really is a discount. Its price is losing the history and never seeing the real numbers.
How to check
Log in with your own email and see whether you can remove someone else’s access. If you cannot, the account is not yours.
P2
How exactly is your fee calculated?
Why you ask
On a percentage model the provider earns more when you spend more. Not necessarily a problem, but a conflict you should know about.
A good answer
Explains the model plainly and says what happens if the budget increases. Raises the conflict themselves if they work on a percentage.
A bad answer
One lump sum with ad spend and fee not separated. Then you know neither how much you spend nor how much you pay.
How to check
Ask for last month’s Google or Meta invoice. It shows the real spend and any gap with the report.
P3
How will we know which ads lead to orders, not just clicks?
Why you ask
A click is a cost. An order is revenue. A campaign optimised for clicks almost always spends more and returns less.
A good answer
Sets up tracking for the specific action before launching ads, and says explicitly that the first weeks are for gathering data.
A bad answer
Launches campaigns immediately. You will get a report of clicks and cost per click, because that is all the system knows without setup.
How to check
Ask them to show how many orders came from ads in the report, then compare with your actual orders for the same period.