Letting the Dom/Domme know in writing if you're interested in something new or have a need that isn't getting satisfied might be a good idea. D. likes for me to write how I feel about the things we do in a journal or in letters to him, and I know a lot of the other Dom/mes give these "writing assignments," too. So if you have a particular concern or desire, it would probably make him feel honored if you wrote him a letter about it, especially if you got hot and heavy with the descriptive writing.