Don’t negotiate around the monthly payment. When you haggle the monthly payment amount, the salesperson has too much room to manipulate the numbers giving the dealership an advantage. This is especially true if you have a trade-in or are financing the car through the dealer. Settle the final new-car price before you discuss the trade-in value or loan terms.

Don’t buy unnecessary extras, such as rustproofing, paint sealant, fabric protection, and window etching of the VIN number. These services are often unneeded or can be bought for less money later. In some cases, VIN etching is pre-printed on the sales contract, but you can simply cross it out and have the salesperson recalculate the total.

Don’t purchase an extended warranty if the new car has a good reliability record. 65% of survey respondents said they spent much more for the extra coverage than they got back in savings on repairs.

Do bring a calculator when financing to verify the amount you’ve agreed to finance matches the terms you’ve negotiated. Some shady dealers will pad the monthly payment in order to add extra costs into the contract, without the buyer being made aware he or she is paying for them.

Don’t drive the car home before the financial paperwork is completely finished. You might get stuck with so-called “yo-yo” or “spot” delivery, in which the dealer calls the buyer back and claims the financing fell through in attempt to force him or her to sign new paperwork with less favorable terms.

Do be prepared to walk out if the salesperson attempts to raise the price you negotiated via e-mail or phone, or if you are uncomfortable with the sales tactics or treatment by the dealer. Sometimes your willingness to walk away is truly the most effective negotiating tool.

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