There are four main types of insurance, according to finance pro Erin Lowry of brokemillennial.com. Luckily, you may already be covered for some or all.

1) Collision—or loss—damage waiver covers accidental damage to a rental vehicle 

If you already own an insured car, your policy often extends collision to a rental—just make sure to ask, Lowry says. “But, for the most cost-effective, fullest coverage, check with the company of the credit card you’re using for the rental. Many major cards cover rental collision—if you use that card to rent the car and decline the rental’s collision damage waiver.”

2) Supplemental liability takes care of medical costs or property damage that you cause

This isn’t often covered by credit cards, but if you own an insured car, says Lowry, most states require your own insurance to provide at least some supplemental liability protection. If you don’t, or you want more coverage, it’s likely worth adding it—many rental companies offer up to $1 million.

3) Personal accident provides you/your passengers medical and death benefits

“This is probably covered if you have health, life, or auto insurance,” says Lowry, “so you’d only buy this for a rental if that’s not the case.”

4) Personal effects protects you up to a certain amount if someone nabs your property from the rental car

It’s often covered by homeowners or renters insurance; if you don’t have those, and you’re bringing valuables on your trip, adding it makes sense. Or, to paraphrase Lowry, just don’t be a dope and leave expensive stuff like laptops in your car.