"Having a printed copy of an appraisal on hand goes a long way in negotiating the value of your trade-in. "
Until you receive a satisfactory car price make sure you take the value of your trade-in out of the negotiation process. If a salesman asks you about a trade-in before you've settled on a price, simply tell him:
"I haven't decided whether I'll be trading-in or not and would prefer not to discuss it until after we've settled on a price for my new car."
Once you've settled on car price and you're ready to close the deal, the trade-in topic will be back on the table. The amount you get for your trade-in can have a big impact on your bottom line, so its worth spending a little time preparing.
Before arriving at the dealership, the first thing you want to do is understand the value of your trade-in. You can start by looking up your car on Edmunds or Kelley Blue Book to get a close estimation of the expected value. However, I strongly recommend you take it a step further and get an actual appraisal.
Many used car dealers will give you written appraisals. If you are lucky enough to live near a CarMax, they will happily give you a free no-hassle appraisal valid for one week- just keep in mind after one week the estimate can change based on market factors.
If you don't live near a used car dealer or just don't want to deal with the hassle, AutoTrader.com lets you enter your trade-in details online and get a free online appraisal valid for 72 hours. If you ultimately decide to take advantage of this offer, you'll just have to go to one of their authorized buying centers (they use a large network of car dealers and garages) and have them verify that the condition of your car is as you specified.
Whether you get the appraisal online or in person, make sure you bring a printed copy with you to the dealership when finalizing your deal.