Step1
DO NOT pick a specific category of vehicle (SUV, sedan, etc.) (DONT GET PIGEONHOLED INTO A CATEGORY. IT REDUCES YOUR NEGOTIATING POWER! Pick at least two of the following types of vehicles *sedan or convertible : SUV or crossover*)
Step2
Pick *four* brands: 1 luxury / 2 mid-market / 1 low price (DONT GET FIXATED ON BRANDS. PICK *ANY* BRANDS, PREFERABLY ONES YOU ARE NOT SERIOUS ABOUT :)!)
Step3
Test drive *each vehicle* from a dealer that *you do not plan to purchase* - print the KBB price / collect the brochures / collect a floor price / collect the 'best offer' / print the Edmunds TMV price - you now have 6 prices for each car in each category (IDEA IS TO UNDERSTAND features / functionality / quality / price across brands and categories)
Step4
Collect *All* the above information in a THICK MANILA FOLDER and WALK INTO YOUR PREFERRED BRAND's DEALER that is *not* nearest to your home (IDEA IS TO GO IN INFORMED, ARMED WITH SIGNALS THAT YOU ARE SERIOUSLY SHOPPING AROUND AND HAVE COMPETITIVE QUOTES! GO WITH A FULL FOLDER INCLUDING COLOR BROCHURES OF THEIR COMPETITION STICKING OUT A BIT :)!) Tip: Don't pick the nearest dealer, because that's what most do and they 'know' you will have to pick them!
Step5
Now, collect *your preferred auto's* info along with ANOTHER auto's info and *WALK AWAY* (e.g. a sedan and an SUV!) (IDEA IS TO GET SPECIFIC INFO ABOUT THE CAR YOU CARE ABOUT WITHOUT DISCLOSING THAT YOU CARE TOO MUCH ABOUT IT!!!!)
Step6
NOW: The most important part - Email / fax a letter to *all* dealers that sell your preferred car and ask for *detailed one shot quotes* to sell you the *specific car that you want with the specific color / options package you care about* (IDEA IS TO SHOW YOU ARE SERIOUS AND THAT YOU ARE SERIOUSLY CONSIDERING VALID 'BIDS')
Step7
SIT BACK AND ENJOY THE BIDDING WAR! Armed with price range information across brands / across categories / across dealers, you WILL GET AN IDEA of how seriously they mark their bids against KBB/ EDMUNDS. Some will cut to the bone from get go, others will be high headed and wont play this game. I like to give them SPECIFIC END OF MONTH / QUARTER deadlines which are at least 3 weeks out! (IDEA IS TO NOT LOOK LIKE YOU ARE IN A TEARING HURRY, YET, NOT MAKING IT SUCH A FAR REACH THAT THEY DONT CARE ABOUT YOUR HELPIN THEIR *CURRENT* QUOTAS!)
Step8
On D-DAY *walk into the dealer that gives you the best price* as close to end of day! PICK THE AUTO *YOU WANT* (helps to be flexible on color!) *MAKE AN OFFER FOR CASH PRICE* *DONT GET 'BOXED' INTO TALKING TRADE*
Step9
LOCK THE PRICE IN WRITING - Then ask for Dealer Finance!
YOU CAN ALWAYS SELL YOUR OLD AUTO TO A USED CAR DEALER THAT WILL PAY YOU MORE!
Sit back and enjoy your new car and new car smell!
*Don't forget to thank the rest of the dealers for their time. If they have been really nice, send their Corporate offices a note and copy them. You never know when you might need them again!
Novice 
