The owner should prepare the car by giving it a thorough interior and exterior clean. Use the following six (6) steps as guidance when selling a car. How much money is the merchant selling the object for?.When completing a bill of sale, both parties must ensure they answer the following questions: It does not need to be complex, nor does it need to contain long-winded clauses. A bill of sale is a form used to prove that a buyer received an object through cash, trade, or gift from a seller.