Before handing over the keys, take pictures and videos of the entire vehicle. Get clear shots of the exterior, interior, wheels, windshield, mileage, fuel level, and any existing damage. Send those photos to the renter and keep them saved with the rental agreement. It takes a few minutes, but it can save you a lot of headaches when the car comes back. You don’t want to argue about whether a scratch was already there. If you didn’t document it, it’s your word against theirs.