I ususally give em about 5-10 minutes to get me a price. DON"T let them ask you if you have a trade in. DON"T let them ask you what you want for monthly payments. if you are going to answer them, just say "i want to focus on the price fo the car, im not concerned with payments and trade in right now. one thing at a time."
they will always ask you "how soon are you looking to buy" and the only "accpetable" answer to them is "today." when they ask you this, just say oh, im not sure, or say soon and only soon. dont say how soon, just say soon. or, say that you are not really concerned with how soon you are going to purchase it. they ususally ask you this when you are lookin at cars on the lot or like when you are storlling in the floor room.
although most salesmen don't like it, if you are "just looking" say that, maybe you are just looking at the car and checking it out after you read about it in car and driver or something.
Just focus on the price of the car. they ask you about trade in and monthly so they can make moeny off you in other parts of the deal, especially in the financing office. Also, nothing is concrete or legal until you sign those papers in the financing office and take delivery of the car.
as mentioned before, don't buy on the first day you go there, unless they give you a killer deal, and by killer deal, it the car you want, and you thoroughly researched price and the car itself, either by means of online or something else; a book.
don't let them know how bad you may want a car. they use that against you.
read all the papers. really. i know it's a lot of stuff, but hey, how do you know what they say you are signing is really what you are signing? and, if you have any questions about anything legal in those papers you sign ask the questions, and the people better be able to answer you.
always ask for complimentary floor mats. asking questons doesn't hurt any.
thats about all i can think of right now from what my father told me about buying cars.