Traveling with twins/kids in general

Okay so i’m a mom of 4. I have 2 sets of twins, i’m 21 years old and i don’t really have money to vacation. However i’m leaving tomorrow with my 9 month old twins (the older set) and leaving my 6 week olds home with close friends. I’m not so much worried about that part but i’m worried about the traveling part. It’s a 8 hour drive to where we are going and i’m honestly terrified. This is our first vacation/ road trip with the twins any tips.