Most parents compare tutors on price and availability because those are the two things easy to see. The differences that affect results are elsewhere. Ask these before you book a first session.
1. Are you a qualified teacher?
Qualified Teacher Status means formal training in how to teach, assessed classroom practice, and daily familiarity with mark schemes and specifications. A subject expert without teaching training may know the maths perfectly and still not know why a particular student is stuck.
2. Do you hold an enhanced DBS certificate?
For anyone working one-to-one with under-18s this should be immediate and unhesitating, with the certificate available on request. Any vagueness here is a reason to stop.
3. How will you work out what my child needs?
Listen for a diagnostic process — questions attempted cold, gaps identified, a plan built from that. If the answer is 'we'll go through their homework', you are buying supervision rather than teaching.
4. Which exam board and specification?
Boards differ in emphasis and question style. A tutor should ask you this before you ask them.
5. What will I hear about progress?
You should know what was covered, what improved and what is next. Silence between sessions makes it impossible to judge value.
6. What happens between sessions?
An hour a week cannot carry a grade on its own. There should be independent work set, and it should be checked.
On price
Rates vary widely by experience, qualification and location. The useful comparison is not the hourly figure but the cost of the whole outcome: a qualified teacher who diagnoses accurately and fixes the underlying gap in ten sessions is cheaper than a cheaper tutor supervising homework for a year.