Car rental offices are very risky unless you have a contract with an insurance company.
Firstly, you have to calculate the price of the car, its rental price, costs to park, its regular maintenance, how much it costs to lose money from accidents and repairs, insurance and its price, when to sell it and how much you will lose from the base price, and how you will compete despite the market filling.
If you can answer all of these questions, then you should look for insurance companies and alternative cars to sign rental contacts for long-term. Also, you should see reservation spaces at the airport and on the Internet or contracts in hotels for rent.
If you don’t know how to expand properly, you will be like those with more parked cars than rented ones.