(MONEY Magazine) – Q. What's the most important thing to do before negotiating?

A. Prepare. For personal transactions, one of the greatest sources for me is the library. There are 1,500 books on how to buy the widget. The next thing is to get comfortable. If I'm going into an environment that I'm unfamiliar with, I go down to the building just to see who the people are, what the arena is like.

Q. What are you looking for?

A. When buying a car, for example, if you see the salesperson go in and interact with the general manager and then the general manager goes back to the salesperson, that should ring a bell: third-party negotiation. Not a negotiation you want. You want to get to a person who can actually sell you the car.

Q. Do you have a cardinal rule for negotiating retail purchases?

A. Determine what the seller is willing to sell for without ever advising them what you're willing to buy for. There may be discount events in the marketplace that have happened from the time you did your research to when you make your purchase.

Q. How do you avoid revealing your price?

A. When he asks, you're gonna say, "That's why I came to ask you. What is the fair price of this car and why?" Then you let him know, "I want to see you make a profit. I know that you're here to make a living." The one thing you don't ever discuss is your ability to pay. They always come to you and say, I'll sell you a car by a monthly fee. That has nothing to do with the price, that has to do with your ability to pay.

Q. What's most difficult to negotiate?

A. It's hardest to negotiate with the mechanic. I don't know anything about cars. I had an air-conditioning element go out on my four-year-old Range Rover. I had a warranty, but they told me it wasn't covered. I asked, "Can you explain to me how you determine what is [covered] and who made that decision?" The determination was made by the person who just repaired the car. So I asked him whether the problem could have been generated by something that is covered, and he agreed that it was possible. He saved me $2,200. With this approach, you find out that people are helpful.

--Laura Washington