You enter with an open mind, try their process for a bit, and see if you feel better. You can even have conversations with them about the timeline they expect for improvement or what they think can actually be achieved -- "goals of care" isn't just for terminal patients. You can be aware of red-flags, if something feels wrong or misaligned you can discuss it or try someone else, but at the end of the day, you can't know for sure if a modality or a relationship will work for you if you don't try it, and give it some time.

I mean, it's the same question as "How do I assess whether my plumber or mechanic or electrician knows what they're doing." Sure, sometimes there's an easy, obvious difference, but you can't really know for sure whether or not your electrician is grounding your entire house to your hot-water pipes unless you have enough skill and expertise not to need one. After a point, working with any professional requires a weird blend of faith and of assessment you don't have the expertise to actually do.