good question! a lot of ERP boils down to collaborative writing, so practicing writing will help with ERP. you can also get mileage out of both communication and casual hangouts with your ERP partner so you can both figure out what pace you're going for, how deep the RP part of the ERP goes, and what kinks you both want to explore or avoid. from my experiences, doing ERP from the dominant angle generally involves painting the world around the sub so they can fully lose themselves in it- a tantalizing setting with the promise of pleasure escalating into overwhelming sensation. at the same time, subs can't be total pillow princesses- you need to make sure you're playing into what your dom is setting up, giving them openings to give you exactly what you want, and of course being vocal (either about what you want or how much you're enjoying it)