I have probably missed the important day, but how did it go?
After 20 odd years of being in and out of the mental health system, there are a few things that can help you. Depending on the nature of the therapist(psychiatrist, psychologist, neuropsychiatrist and so on), there are certain things you can do to prepare yourself for future visits.
Take notes between visits so you do not feel anxious "being on the spot" in a session. It will help you remember what you want to talk about.
Psychiatrists often function on logic and medicine. A lot of them will speak purely about symptoms and pathology. They are the ones that can prescribe you medication. Also, a shrinks appointments are generally much shorter than a psychologists, so be prepared for when you go so you get the most out of your session. Feel free to argue their logic or reasoning, but have some constructive arguments to shoot back at them.
Do some research on the place that you are visiting for therapy. Often they will have short bio's on the therapists there and their speciality. They will also speak of their companies' ethos and general standard of practice.
If there is something that comes up in the future that you do not agree with or you would like a second opinion, request it. It is your right as the client to get a second opinion.
And finally, you are the customer. They work for you, not the other way round, and if they are a decent therapist, they will take the time to build trust and respect with you. Trust and respect between client and therapist is paramount to getting good therapeutic outcomes.
I wish you the best of luck.
Mics