Be familiar with common strategies employed by dealerships and sellers. For example, MSN Money
warns against the "four-square" trick. (I've had this one used on me.) In this trick, the salesperson draws four boxes with a number in each: your old car's trade-in value, the new car's price, the down payment, and your monthly payment. "From there, the salesperson begins crunching numbers -- most likely making it too hard for you to follow," writes MSN. He or she will shift your focus to the monthly payment, which can result in a longer loan and a higher interest rate.
Another common trick is to heighten your sense of urgency, says Business Insider
via Gregg Fidan, founder of RealCarTips.com and the author of "Honest Guide to Buying a Car." For example, the dealer may tell you "that color is not available; there's only three left statewide; the price is good only for today; someone else is interested in the car, better decide quickly, etc." In this case, be patient and courteous, but remain level-headed and never rush to buy. Study up on Fidan's list of 112 car-buying scams
To sum up the list: Don't let yourself get too caught up in the excitement of shiny metal, and remember that in six months that "new car excitement" will have faded, and you'll be due for an oil change.