Before You Go
Check if your personal homeowner's, credit card, or auto insurance provides CDW coverage, and if so, the limits and any restriction on vehicle makes or models. However note that in some countries, such as Ireland, Italy, and Turkey, third party coverage is not accepted. You can also add coverage for rental cars to your travel insurance policy for reasonable rate.
Make sure you have a large enough vehicle for passengers AND luggage, especially if you will be driving between hotels often.
Check if an international driver's license is required in your destination. Even if it isn't, the small fee to get one can be worth the peace of mind & time savings in case you are pulled over by an officer who is not fluent in English.
When You Arrive
Make sure you understand the rental contract you are signing. You can request the rental agreement in English from most of the larger companies. If you do not want extra insurance, make sure you do not sign for it in error at the counter.
Inspect the interior & exterior of the vehicle before departing, and take pictures with your phone.
Check what kind of fuel the car uses, gas or diesel. Most car companies provide a full tank and you are expected to return it full. But make sure you understand the conditions so you don't fill the tank and then also get charged for a full tank.
Make sure you have the numbers for roadside assistance. If you've rented from Auto Europe, you can also call them toll free 24/7 with questions or to request assistance.
When You Return Home
Hold onto receipts for at least six months.
Check your credit card statement. Most traffic violations are captured by camera & sent by mail. If the rental company receives a citation, they'll automatically charge your credit card.
Check the exchange rate on the day of your rental. If the exchange rate is higher than when you booked the car, you may be entitled to a refund. If it's lower, you saved money!