Sub trying to dom

My man is a switch, I am typically sub and he's dom but he's been asking for me to be more dom and I just am clueless. We've talked about limitations on language and what he would like or not like but I'm just not really comfortable yet with it, like I feel clumsy and dumb trying to say things or do things when I'm usually recieving. Any clues on how to get in the dom mindset especially when you have really only been sub? Any tips and tricks are welcome, obviously we are safe and use safe words and stuff I'm just trying to figure out how to 180 my role and not feel like the worst actor in a B rated movie. He thinks I do fine but like we've only done it twice and I'm still feeling nearly embarrassed because I dont think I am doing a good job.