I bought a new car last year for the first time(previous two car purchases had been used cars). I wouldn't say I'm an expert at it by any means, but I was pleased with how it turned out. Before going into the delearship, I got a copy of my credit report, printed off the invoice/retail pricing of the car I wanted along with the appropriate options, and printed off the blue book value of my car for trade in. I visited the dealership on a Sunday and browsed the cars they had on the lot so that I could find the color and options package I wanted without a salesman hassling me. I went into the dealership the next weekend with all of this information, found a salesman, and told him which car I was interested in. After a quick test drive, we went into his office. I told him that I was ready to buy the car from him that day if he could meet three requirements that I had. I pulled the printout of the invoice pricing for the car with the options it had and said I wanted to pay invoice for the car, then pulled out the blue book value pricing for my trade-in and said "you will give me this for my car," and then pulled out a printout of the current financing specials they were currently running(it was like 3.9% I think) for new cars. I told him that I'd write him a check for a substantial downpayment if these requirements were met. After a few trips back and forth to the sales manager, I got the car for invoice(something like $3K off the sticker price), got what I wanted for my trade-in, and got the financing deal I wanted. I was prepared to walk out at any time if one of those requirements wasn't met.
Be sure to go in there armed with invoice info, otherwise you're going to be working from the sticker price down, as opposed to from the invoice up.