Eaither way:

There is a simple way to get around the whole saying no thing that I picked up over the years. (first used on me to get me to stop speaking without permision)

Outside of the so called "safeword" invocation or refusal of a task and or revocation of one's submission:

try going for the next week without saying the word "no"...to anyone and everyone you speak with.

Yes everyone, friends , coworkers, your children, the nieghbors dog,etc. Short of screaming "No" in a saftey situation etc. You simpley learn how to phrase your responces differently then.

Of course one will need incentive.

Keep a lil notepad in your purse, or a clicker to count with for each infraction on each day.

You can eaither be earning orgasms or some other such suitable reward for each day with no misshaps and for each infraction you can recieve a suitable punnishment, which should be sufficently unpleasent enough for you to not want to be recieving it, yet not be so bad it damages you or fills you with dread (ie it should be a sutible negative inscentive for you). You can even add some extra special punnishment for each time you say "no" directly to your dominant as an added bonus.

Trust me it works, you will be surprised how fast too. Dont forget here are numerous variations to it it and entire behavioral modification type things this simple pavlovian technique can be used for other than just the word no too.

Like involuntary orgasm control....winks.