Choosing between a convertible and a sedan? Easy. Deciding what, if any, insurance you need? Much trickier. At the rental counter, you’ll be offered a collision-damage waiver (CDW), which relieves you of financial responsibility for theft or damage. The clerk might also offer you liability, personal-accident, and personal-effects insurance for an extra charge. Take these steps ahead of time to know how to decide.

Check all your existing insurance policies. If you have auto insurance that includes comprehensive and collision coverage, it should also cover theft of and damage to the car and liability. Your health insurance may already cover you for personal accidents. Home owner’s insurance may cover thefts from the car.

Once you’ve confirmed this information with your insurance carriers, you can decline that extra coverage, says Jeanne Salvatore, a spokesperson for the Insurance Information Institute.

Call your credit-card companies to see if your cards offer some type of insurance protection, especially if you don’t have auto insurance. Coverage varies and can depend on the card status (gold, platinum) and the bank. So it’s worth a phone call before you decline the CDW or other options.