I am a big believer in children learning negotiation. To some, that makes me an ineffective parent or worse - a waffler. But, I am convinced that children who never get to put in their two cents will be ineffective adults. They will be adults lacking confidence and verbal skills.
HOWEVER what I have learned the hard way is that you have got to decide AHEAD of time whether the issue you are dealing with is negotiable or not.
There is nothing worse than switching from the "no means no" horse to the "maybe horse" midstream. When you switch horses midstream, you lose credibility and you may get confused about what your initial plans were. And of course, you set yourself up for a lot of whining in the future.
My youngest child is too cute for his own good. When he was little, it was hard to say "no" to that sweet face. So many times, I would say "no" and then after a few sad looks would change my mind and say "yes, but just this once." MISTAKE.
We have walked a long hard road through many tantrums to get to the point where he takes us seriously. After a few years of hard core parenting, we have gotten him to see that "no" does mean "no", at least most of the time. He is still cute, but his whining and determination to get is own way is not so cute.
What we needed was a cue. A cue that signals to the overly cute child that “I mean business.” Or the reverse; “Give me a good argument and I may flex a little.” Those words can be hard to find at the spur of the moment.
I leave you with some words to keep in mind when you might want to set a negotiable limit. "Right now I am thinking that you will not be able to....but...." or "I am not sure what to say about that right now. I will get back to you later." Or lastly, there is the old favorite: "I have to talk to your father (mother) about ....before I make a final decision." Its always nice to have a fall guy if you need one.
