Step zero is to be really aroused, until you’re naturally lubed to the same degree you would be in your own self pleasure. it’s important to be honest with yourself about whether you’re into it and whether he’s making it really enjoyable for you in the moment! That said, if you are having a good time but just don’t have enough natural lube to reduce the friction, adding lube is definitely a good tip. (use a product made for that purpose, please don’t improvise lube with other products)