Reading Tarot for Other People (Without Doing Harm)
The technical part is the easy part. Here are the boundaries that matter, what to say when a reading turns heavy, and what changes when money is involved.

The first time somebody asks you to read for them is a different experience from reading for yourself, and the difference is almost entirely ethical rather than technical.
You already know the cards. What you probably have not thought about is what happens when a reading lands somewhere painful, what to do when somebody asks about their health, or how the whole thing changes the moment money is involved.
The rules that matter
Five, and they cover most of it.
Do not read on health. Not "is this lump anything", not "will the treatment work", not "should I stop taking this". Tarot does not diagnose, and the harm of a wrong answer here is not symmetrical with the benefit of a right one. Say so plainly and mean it.
Do not read for a third party who has not asked. "What is my sister really thinking" is a question about somebody who is not in the room and did not consent. The most a reading honestly reaches is what is being expressed into a situation from where the querent sits, and that boundary is worth stating out loud rather than quietly working around.
Do not predict a death or a diagnosis. Death is a card about transition and it lands in readings constantly. Somebody who does not know that will hear something you did not say, so get in front of it.
Do not tell somebody something they cannot act on and will not forget. This is the one people miss. A reading that leaves a person anxious about something they have no power over has taken more than it gave. If the only honest thing you can see is unpleasant and unchangeable, the skill is in what you choose not to say.
Say when you do not know. Every reading has a boundary. Naming it is the difference between a reading and a performance, and it is also what stops you inventing detail to fill a silence.
Set the frame before you start
Two sentences, before any cards come out. Something like:
This describes the shape of a situation rather than predicting what will happen, and nothing here is medical, legal or financial advice. If something comes up that you would rather not go into, say so and we will move on.
That does three things at once. It sets expectations, it gives them permission to stop, and it means you are not renegotiating any of it halfway through a difficult card.
The spread does some of the work
A spread with the right positions makes ethical reading easier, because the boundary is built into the layout rather than something you have to remember.
Reading for Someone Else is laid out for exactly this. Three positions are the reading: where they are, what is pressing, what would help. The fourth is what this cannot see, which exists to be read out loud. The fifth is what you are bringing to it, which is for you rather than for them.
That last one matters more than it sounds. Readers project, particularly onto people they know, and a card that names your own investment in the outcome is worth drawing before you say anything.
When a reading turns heavy
It will. Somebody will draw Three of Swords and start crying, or a shadow position will land on something real.
What to do:
Stop reading cards. The instinct is to keep going and find something reassuring. Do not. The reading is no longer the useful thing in the room.
Say what you see plainly and without decorating it. "That looks like it landed. Do you want to stop?" is better than anything you could improvise about the card.
Do not become their therapist. You are not one, and the fact that somebody is telling you something painful does not qualify you to treat it. Tarot is a reflective tool. If what has surfaced is genuine distress, the honest thing is to say that a professional is the right next step, and it is not a failure of the reading.
Do not read again to soften it. Drawing more cards until the picture improves is the clearest way to make the whole exercise meaningless.
Reading for friends and family
Harder than reading for strangers, for one reason: you already know the answer you want them to hear.
If you think your friend should leave their partner, you will read Eight of Cups as walking away and you will not notice you did it. That is not dishonesty, it is how reading works when you have a stake.
Two mitigations. State your investment out loud before you start, even if only to yourself. And read the cards you would rather not: if a card contradicts what you were hoping the spread would say, that is the one to spend time on.
Reading for yourself covers the same problem from the other direction.
What changes when you charge
Charging is legitimate. Readers have always been paid and there is nothing corrupt about it. What changes is that you have acquired obligations.
A duty to be clear about what they are buying. Reflective reading, not prediction, not therapy, not medical advice. Written down somewhere they can see before they pay.
A duty not to create dependency. A reader who encourages weekly readings about the same unresolved question is selling reassurance rather than insight, and it is the commonest way this work goes bad.
A duty around vulnerability. People come to paid readings at the worst moments of their lives. Some of them will be in no state to make a decision about spending money, and noticing that is part of the job.
A legal frame. In the UK, consumer protection rules mean this kind of service is generally offered for entertainment, and saying so is not a get-out clause so much as an accurate description. Different countries handle it differently and it is worth knowing your own.
The ethics of reading for other people goes further into this as a lesson.
The short version
You are giving somebody a way of looking at their own situation. That is genuinely valuable and it is smaller than what they may want from you.
Most of the harm in this field comes from readers who accepted a larger role than they could hold: predicting, diagnosing, or knowing another person's mind. Declining that role is not modesty. It is the job done properly.
Frequently asked questions
Is it OK to read tarot for other people? Yes, with boundaries. Do not read on health, do not read for a third party who has not asked, do not predict a death or diagnosis, and say when you do not know.
What do I say before a reading? That it describes the shape of a situation rather than predicting events, that it is not medical, legal or financial advice, and that they can stop at any point.
What if someone gets upset during a reading? Stop reading cards. Say plainly what you noticed and offer to stop. If it is genuine distress, a professional is the right next step and saying so is not a failure.
Can I read for my friends? Yes, and it is harder than reading for strangers because you already have a preferred answer. Name your investment before you start and pay attention to the cards that contradict it.
Should I charge for tarot readings? It is legitimate. Charging brings obligations: be clear what is being bought, avoid creating dependency, and be careful with people who are not in a state to be spending money.
Can tarot tell me what someone else is thinking? No. A reading reaches what is being expressed into a situation from where the querent sits, and no further. Any reader promising more than that is telling a story.