Worth knowing before you start, and rarely said by people who are selling it.

Almost everything written about this is written to persuade you to try it. So the limits go unmentioned, and people arrive with expectations that were never going to be met, and leave concluding it does not work. Here is the other list.
This is the most common one. Someone comes because of a partner, a parent, a boss, and hopes to leave with an instrument that will produce a change in that person. I have no such instrument. What can change is your part of the pattern, what you are willing to live with, and how much of your life the situation occupies. Sometimes that shifts the other person too, because patterns need both participants. But it is a side effect, not a mechanism, and I cannot promise it.

People sometimes want the answer. Should I leave, should I take the job, should I have the child. I will not tell you, and not out of technique. I do not know, and neither does anyone else who is not living your life. What I can do is help you find out what you actually think, which is often obscured by what you believe you ought to think. That is genuinely useful and it is slower than being told.
There is an expectation that the grief, the anxiety, the anger will be taken away. Extracted, and you leave without it. What tends to happen instead is that it becomes something you can carry rather than something that carries you. The volume changes. Its authority changes. You stop organising your week around avoiding it. That is a real change and it is not the same as removal, and it is worth knowing which one you are signing up for.
If someone is in genuinely unsafe housing, or under financial pressure that has no give, or in a relationship where they are frightened, an hour a week is not going to fix the situation. Nor is it useless — but it would be dishonest of me to imply that talking resolves conditions. Therapy is not a substitute for a lawyer, a doctor, a different job, or leaving.
I am not a psychiatrist. If medication is worth considering I will say so and help you find someone who can assess that properly. If somebody offering therapy tells you that you do not need medication, treat that as a reason to be careful.
This is the one people find most annoying and it is the most important. You can attend faithfully for a year, answer everything asked, and change very little, if the thing happening in the room stays at the level of reporting. What moves things is the willingness to look at something you would rather not, in front of another person, repeatedly. I cannot supply that. I can make it as safe as possible and I can notice when we are both avoiding something, and I do. But the willingness is yours.
Some people do not get on with it. Some get more from a different modality, or from a group, or from a change in circumstances, or from a friend who is better at this than most therapists. If we are three or four months in and nothing has moved, that is worth saying out loud rather than continuing out of politeness. I would rather have that conversation than keep the appointment.
Because expectations that were never realistic are one of the main reasons people conclude it failed, and because a practice that only ever describes what it can do is telling you half of something.
Written by Satlaj Sachan, a counsellor in Bengaluru working Book a first conversation.