Most bad readings are lost before the cards come out.
Agree the Question
"Just see what comes up" produces a reading that cannot be wrong and therefore cannot be useful. Every card fits, nothing is confirmed, and the querent leaves with a pleasant fog.
Spend two minutes getting to something answerable. Not interrogation — you are not extracting the answer in advance — but enough shape that the reading has something to be about.
"Will I ever be happy?" becomes, with a couple of questions: "What is in the way of me leaving this job?" Same underlying ache, and now the spread can say something.
If the querent genuinely does not know what they want to ask, that is itself the reading. Draw to what should I be asking? and work from there.
Say What This Is
One or two sentences at the start prevents most of the harm tarot can do:
"This is reflective rather than predictive — I'll tell you what I see in the cards, you tell me what matches, and nothing here is fixed. And if anything comes up that needs a doctor or a therapist, I'll say so."
Nobody has ever been put off by this. It sets you up as a reader rather than an oracle, which is a far easier role to occupy for an hour.
Ask What They Want From It
Different querents want different things and they will rarely volunteer which.
Some want a decision made for them — which you should decline, kindly. Some want permission for a decision already made. Some want to be told they are not imagining it. Some are curious and want a show.
"What would make this hour worth it for you?" gets you there in one question.
Set the Boundaries You Need
If you do not read on health, pregnancy, death, or third parties, say so before you begin, not when the question arrives.
Announcing a boundary mid-reading, in response to a specific question, reads as a judgement on the querent. Announcing it at the start reads as professionalism.