Car sickness is horrible for long car trips and will make the trip unpleasant. Here are a few ways to prevent motion and car sickness.
1) LOOK OUT THE FROUNT WINDOW. Watching the passing scenery can confirm your balance system's detection of motion and help resolve the mismatch that causes car sickness.
2) SIT IN FROUNT. Consider driving (if possible). Drivers rarely get car sickness as they are always focused on the road. Sitting in the passenger's seat up front is the next best thing.
3) CLOSE YOUR EYES. Sleep if you can. If your eyes are closed, you don't see anything, and that removes the cause of motion sickness.
4) OPEN A WINDOW. If it is not possible to open the window, lean towards the bottom of the window and breathe. There should be leaks of air.
5) TAKE BREAKS. Go outside to stretch your legs. Sit on a bench or under a tree and take some deep breaths in through your mouth, breathing deeply from your stomach to help relax.
6) Other good things to try eating are ginger candies (chewable), ginger coated in sugar (if you don't mind the heat of ginger) or ginger mints.
7) Fresh mint can also cure or alleviate nausea. Buy it in the produce section of the supermarket. Start by eating 2 leaves and feel free to eat more if you need it.
Those are just a few ways to prevent motion sickness. Have a nice day and drive safely.