For many people, negotiation is the worst part of a transaction, whether it's buying a car, getting a new job, or entering into a business partnership. 

But it doesn't have to be. You can become a truly great negotiator by cultivating a single tool: the power of a positive attitude. 

You might roll your eyes here -- but wait! Academic research has demonstrated that positivity is the key to great negotiations. As the paper I just hyperlinked to notes, "The single best predictor of negotiation performance is positive expectations." 

So how can you develop it? 

Practice, practice, practice
By practicing negotiations, you can help yourself develop the belief that you will succeed in future negotiations. This is a key part of a positive attitude: simple self-belief.  

Whether it's attending a class, seeking out new negotiation scenarios, or even preparing for and "acting out" an upcoming negotiation with a trusted colleague, find ways to practice the skill. The more you do it, the less intimidating it will become -- and before you know it, you might feel like a pretty good negotiator. 

Once you've developed that confidence, a positive attitude about the potential outcomes will follow. 

Think of all the potential outcomes -- not just the bad ones
We can borrow another tool for cultivating positivity from behavioral psychology.

Think about a tough negotiation you had. Were you mired down thinking about how everything might go wrong? Were you worried about overpaying for the car, getting a lower salary than your colleagues, or having the wool pulled over your eyes in that big business deal? 

Those situations are all a bummer, and they can be hard not to think about. However, the worst possible outcome is never the only possible outcome.  

Next time you enter into a negotiation, think to yourself, what is the best possible outcome for this negotiation? What will maximize my own interests? Then think about all the other potential outcomes. Maybe you'll overpay a little for the car, or maybe they'll throw in the maintenance plan for free. 

In other words, think about all the possible outcomes. This will help you come up with ideas about the different combinations of trades that you can make -- maybe there are several that would leave both parties happy at the end of the day. 

Match your negotiation to your personality
Do you prefer to cooperate rather than compete, or maybe the opposite? In either case, try to favor negotiations that best suit your personality. This is an easy way to build up your confidence and your positivity. 

For example, a more cooperative negotiating style might be the most appropriate way to deal with your child's baby sitter, while a competitive approach could be better suited for buying the new car. The same holds in business: A new client might call for a more cooperative style, while a supplier relationship could be best cemented with tougher tactics. 

To the extent possible, use your existing personality characteristics by engaging in negotiations that fit with your character. This will not only help you build tools in accordance with your existing traits, it could help you find the confidence and optimism that will make you even better in the future.

But remember, personality isn't destiny
That being said, being a cooperative person doesn't mean you can't succeed in a competitive negotiation. Remember, the most important factor in success isn't your personality, it's your attitude. 

So how can you adapt? 

It's all about learning everything you can. Find a colleague  with a different negotiating style and see if you can act as a shadow to observe and learn some new techniques. How does your colleague frame an opening offer? Respond to a counteroffer? Protect their self-interest? 

By breaking down your colleague's style into a set of tactics and strategies, you'll be able to build a tool kit that works for different scenarios and negotiations outside of your comfort zone. 

From there, practice and prepare. Try out your new tools on your friends and loved ones (with their consent, perhaps), and test different frameworks on each negotiating situation you find yourself in. Brainstorm ideas that fit more easily with your personality, and then do the same thing using your "second" toolbox. 

It will require practice, but you'll find that, with time, it will become easier to find the most appropriate tools for a given negotiation. 

And then, suddenly, you might notice that you've become that person everyone comes to for help -- being, as you are, a great negotiator.