Starting ERP!

Hi! I made a post on here a couple weeks ago seeking advice for doing ERP on my own without a therapist, and some things have changed and I was luckily able to schedule an appointment with an OCD therapist! I am relieved and ready to start this journey, but I'm also scared that I won't be able to articulate myself well and that I'll be too scared/nervous to be honest about my OCD. For those of you who have done ERP with a therapist, do you have any tips about how to prepare mentally? And to ensure I make the most out of the sessions? Thank you!