A little planning goes a long way toward making an international road trip relaxing instead of stressful.
Map out your route in advance and build in more time than you think you'll need — unfamiliar roads, fuel stops, and scenic detours all add up. Download offline maps in case you lose signal, and note the locations of fuel stations along rural stretches, since they can be sparse outside major towns.
Check parking rules in city centers before you arrive; many historic European town centers restrict vehicle access entirely, and towing for wrongly parked cars is common. Booking centrally located parking ahead of time can save real frustration.
Keep a printed backup of your route and reservations in case your phone battery dies, and always let someone know your general itinerary if you're heading into remote areas.