Keep in mind that just because it sounds as if you're disagreeing, it doesn't mean you actually are. Think twice before you grimace, snarl or bark at the other side. First, make sure it's not a simple miscommunication. Isolate the phrase that makes you bristle, and ask your opponent, "When you say such-and-such, what exactly do you mean?" Also, consider whether it's the tone of voice or attitude that tweaks you. For example, some people always sound as if they're yelling; it's not about you or your deal-that's just the way they talk. In many cases, you'll find there's no dispute and nothing worth arguing about.
On the other hand, once it's clear you disagree with your opponents, it's crucial to probe beneath the surface and find out what they really want. This might sound trite. Emptor emit quam minimo potest, venditor vendit quam maximo potest, or "the buyer buys for as little as possible, the seller sells for as much as possible." But consider this classic scenario: Two kids squabble over the last orange in the fridge. Their father hears the ruckus, enters the kitchen and, without a word, thinks of a solution: He slices the fruit in equal halves and gives one to each child. Yet they're each disappointed. Why? Because one kid wanted to eat the pulp, and the other just wanted to bake with the rind!
Don't jump to conclusions. Try to uncover the other side's underlying interests. What you learn may not only surprise you, but also pave the way for an easy solution. Often, differences are what make agreements possible. Why settle for either/or when you can have win/win?