Ugh. We REALLY try to use phrases and words that frame things positively (like instead of saying "don't jump on the couch" we'll say "please use your inside feet") and yes I know that the idea of "inside feet" is a bit strange.....but ds "gets" inside voice, inside feet, etc.
Even at that, he still says no ALL the time.
One thing that helped me was inventing the "no" song. I'll say "are you ready for breakfast?" "no." "Well, would you like to eat and then get dressed, or get dressed and then eat?" "I NO get dressed! I NO eat! I NO like you!" "Are you feeling grumpy? Do you want mommy to give you a hug to cheer you up?" "I NO want hug!" "Are you in the mood to say no?" "I NO say no!"

And then I sing the no song and he usually starts giggling and singing along and then we get on with whatever needs to happen.
The no song is (sung to the tune of BINGO)
"I know a little boy,
and all he says is no.
No, no, no, no, no,
no, no, no no no,
no, no, no no no,
His favorite word is....."
and then ds yells "NOOOOOO!!!!!" and starts laughing hysterically.
I have no idea why this works, I guess because I'm embracing the "naughty" word, but it definitely diffuses the impending tantrum. he will even sometimes ask to sing the "no song"

no idea if that would help you, but you can try it.
Now if you can come up with a solution for the constant "I want...."