Be sure to verify exactly what the rental rate covers before you leave. “We tell our clients to budget for the three G’s: groceries, ground transportation and gratuities,” says Smith. Typically you’ll pay for airport transfers, food and drink, and additional services such as excursions, spa services and, in some cases, child care. Remember that gratuities are not optional: “We recommend 10 percent of the rental cost during high season and 15 percent in the summer,” says Smith. You can choose to prepay tips to your agent, who will distribute them to the staff, or use cash at the end of your stay.