It’s hard to get off the beaten path unless you drive. Driving in another country can be intimidating unless you do some advance planning. Here are some tips that may help.
Disclaimer: I am not an expert at this. Do your own research to make sure you can drive safely.

General tips
• Get an international driver’s license at a AAA office. You don’t have to be a member. They cost around $20 and are required to pick up your rental car.
• Pay the extra for insurance unless you have international coverage through your credit card. My AmEx charges a flat fee every time I rent and provides primary coverage. Call your credit card company to make sure you have coverage.
• Rental cars with automatic transmissions are not at all common in Europe and they cost more. However, it’s worth the extra expense unless you are very comfortable driving a manual transmission.
• Rent the smallest car that will hold you and your luggage. Roads and streets can be very narrow. Even with a small car, I find parking to be a challenge with sometimes just a few inches of clearance on each side.
• Just like in the US, some roads have tolls. That can be confusing when you don’t know what to expect. Check in advance about toll roads in the countries you’re visiting.
• Some countries (like Austria) require stickers. You can get those at convenience stores, but it’s much easier to buy them in advance. Do a Google search. Here’s one source.