Information is your best friend. Gather all the prices you can about the model you're looking to purchase, including invoice, cash back, rebates, and market price. Price out the model you want to buy, shoot your offer to 3 dealers. The best one, in terms of pricing and service convenience, gets the deal. Get an estimate over the phone for your trade, subject to final inspection. Most used car managers (the guy who actually does the appraisal) worth his salt can quote a trade in price over the phone in 3 seconds flat, provided you're up front about the condition of your car. If you lie, they'll find out, then make your time miserable when you're at the dealer negotiating over every penny. So, to sum it up: get all the prices together, then make them a reasonable offer (gross margin depending on the make/model), and be firm on it. You'll be in and out in an hour, and you won't lose any sleep over whether you've gotten the best deal. Or, pay me $500 and I'll negotiate the deal for you, over the phone.