I would offer that too much "no" could become an issue. Obviously you don't want to be doing anything that hurts or is demeaning to you. Just be careful that sex doesn't become all about your fantasies and needs and wants and don't address his. If you don't want something, don't expect reciprocity.
Communicate and compromise and work out what works best for both of you so you can both give as much as possible to the other.