In my house, the word "no" comes in different stages. There are the "no's" that answer every question they don't want to do..."no, I don't want to go to bed", etc. Then there is my tween age daughter who starts every sentence with no.
Me: "Is that chocolate I see all over your face?"
Her: "No, I just ate a bowl of ice cream!"

I'm sure the latter isn't the 'no' you're asking about, but to answer your question, when my children tell me 'no', I stand very firmly upon my ground. See, I'M the parent, and even though my kids may not like what I've asked them to do, they know that 'no' isn't an option.

When they were little I can remember saying things like "please pick up your toys" and when that was followed with a 'no' from them, I would get down on their eye level and say "yes, you are going to pick up your toys. We can't leave a big mess in your room", and I would help them pick everything up. I think that gives them verbal reassurance as well as physically showing them that you mean business without having to get too forceful with them.

We've had a few cases over the years of 'no's' being loud, stomping, fits, but for the most part this approach has always worked for my kids and they've grown up to understand that when mom says do, they do.