Ask: have YOU sat the exam?
Tutors who haven't actually sat the DELE often teach the wrong things. The exam tests specific genres — formal complaint letter, argumentative essay with cited authorities — that generic Spanish lessons skip. A tutor who has sat the C1 and passed knows exactly what's tested and what isn't.
Ask: what's your pass rate?
Honest DELE tutors track their pass rate per cohort and per level. If a tutor can't tell you their C1 pass rate over the last two cycles, they're guessing what they teach. Good tutors clear 85%+ at the level they specialize in.
Ask: what does your weekly rhythm look like?
DELE prep needs 4 sections worked separately + 1 timed practice exam every 3 weeks. If the tutor's plan is 'we'll just speak Spanish and see how it goes,' walk away. Ask to see their week-by-week plan in writing.
Look for graded written feedback
C1 essays are the killer section. The right tutor returns YOUR essay marked up with the same rubric the examiner uses — coherencia, riqueza léxica, gramática, propiedad léxica. Generic 'looks good!' feedback is a red flag.
Check their cohort dynamics
Cohort prep beats 1-on-1 for DELE because peer essays + peer oral practice expose you to the variety the exam will throw at you. The best DELE tutors run small cohorts (4-8 students); cheaper options that pile 15+ into one cohort dilute the feedback loop.