SEO is the one service here where you can pay for two years and still not be sure what happened. That makes the questions matter more than the offer.
What you are actually buying
You are buying two things: technical work on the site itself, and content that answers what people actually search for. Everything else, links included, follows from those two.
The most important thing to know before the first conversation: traffic is not a professional metric. It can be raised trivially with topics that have nothing to do with your business, and some agencies do exactly that. The real question is what share of commercial-intent searches reaches you, and what it produced.
What each budget realistically buys
25 – 150 € / month
This buys a few hours. Enough for a report and small fixes, not for strategy and content. Not a scam in itself. It becomes one when sold as "full SEO optimisation".
400 – 1 200 € / month
Real monthly work: technical upkeep, a few pieces of content with reasoning behind them, analysis of results. The range where most SMEs see movement after four to six months.
2 000 € + / month or per project
Audit and strategy for a large site, a shop with thousands of pages, several markets. Often paid once for the analysis and separately for execution.
The first questions
S1
Which metric will you report to me on, and why that one?
Why you ask
The answer to this tells you almost everything. Traffic and rankings move easily and do not mean revenue. Whoever offers them as the primary measure either does not know, or is counting on you not knowing.
A good answer
Ties the work to something the business counts: enquiries, orders, calls. Admits the first months are reported on intermediate signals, and says which.
A bad answer
"We will increase traffic" or "we will get you into the top 3". Nobody can guarantee a position, and anyone guaranteeing one knows it.
How to check
Ask to see a sample monthly report from another client with names removed. If it contains only rising graphs and not one sentence of reasoning, that is what you will get.
S2
Whose account will Search Console and Analytics live in?
Why you ask
This is your site’s history. If it sits in the agency’s account, ending the relationship costs you not the service but every year of data before it.
A good answer
Your account is the owner, they get access you can revoke. They say so before you ask.
A bad answer
"We manage them and send you reports." A report is an interpretation. The data is a fact and it should be yours.
How to check
Log into Search Console with your own email. If you cannot see your site, or cannot remove someone else’s access, you are not the owner.
S3
Who implements the changes on the site, and is that included in the price?
Why you ask
A large share of failed contracts fail here. Recommendations are written, nobody is available to implement them, six months pass and nothing on the site has changed.
A good answer
States clearly who touches the site, how many hours a month are allocated, and what happens if your developer cannot keep up.
A bad answer
"We will hand recommendations to your team." If you do not have a team, that is an offer for a document, not a service.
How to check
At the end of each month ask one thing: what specifically changed on the site this month. If the answer is general, probably nothing did.