As an owner of an independent car rental business, this is what I do when I rent a car:
I have a comprehensive personal auto insurance policy that extends coverage to when I rent a car.
I am signed up for the Amex Premium Car Rental Protection plan. Although this costs me an extra $25 per each time I rent a car, I know if there is a fender-bender, Amex will act as primary coverage and it will not go on my personal auto policy (potentially increasing my rates).
I decline any offered insurance coverages from the rental car agency, such as CDW/LDW/PDW, personally accepting full responsibility for the vehicle. This is required if something terrible does happen in order for my personal auto and Amex plan to be able to work.
I decline prepaying for fuel or any of the other million things the agent tries to sell me on.
Follow these steps and you will be as good-to-go as possible!