it's really scary going into a pysch appt for intake - it's intimidating, but what the others said, be honest, open, and really try to be transparent so they can help you as much as possible
ask questions about anything you're curious about, that's what they're there for -- if they prescribe you medication, ask how it helps, what the side effects are, what to expect
knowledge helps ease apprehension and worries, and just make sure to take deep breaths, it will be difficult, but it'll be worth it