I make a long trip every year with 2-3 students, so I'm very careful about this!
My husband is a mechanic, so he checks the car out thoroughly. Fluids, tires, brakes, lights, etc. If you do not own your own mechanic? Hire one to check out the car! Make sure the car is safe for a long drive. Make certain you have a spare tire and know how to jack and change a tire. Make certain your debit card has 2K in case of an emergency. Have a travel plan (itinerary) with everyone you're traveling with.
Now that you're sure 100% that the car and money are good? HAVE FUN. Stop and take pictures. Visit that weird place. Stop and shop and visit. Bring back souvenirs. That totally stupid and awesome fridge magnet? You bet!
Bring lots of water, sunscreen, moisture for your lips. Be safe. Don't ever be afraid of calling for help.
On long road trips when you're responsible for other people? GAS UP at 1/2 a tank! Have snacks, water, blankets.
If you're stuck on the side of the road? Learn the Boy Scout Salute. It has saved my entire trip. I had three students with me, and our tire was blown. I didn't understand locking lugnuts. I held up the Boy Scout Salute and two cars later? A gentleman stopped and changed the tire.
Remember on the road, most folks want to help.