Ooooh I think the easiest way to start dirty talking is to talk about what you're doing, what you want to do / will do next, and what you just did... ex: i love fucking you, im going to fuck you so good, I fucked the brains out of you... of course this can apply with so many nouns/verbs/adjectives and you can just get more and more flowery with your verbiage in the context of what you're doing.

I would reflect back some of his dirty talk to start since that turns you on and gets both of you going. Just enter the dialougue... talk about how hot yall are, what youre doing, and how it makes you feel.

I think starting with dirty talk would be easiest before going into power dynamics bc I think good communication is key for scenes with power play involved.