The difference between the best deal and a fair deal is all about mindset. In almost any case, striving to do the best deal for your side requires a less-than-best deal for the other side. On the other hand, there’s a lot more room for all to win if you’re looking for a fair deal for all.
Understand my own bias up front. I’m a bad negotiator. While I get irrationally upset when I think I’ve been treated unfairly, I’m perfectly happy leaving money on the table if I think I’ve got a fair deal.