The very first tip you should remember is keep busy. Trick your body into thinking that there is no motion happening under you. Keep your eyes straight ahead and enjoy the view of the road. Amuse yourself with anything you spot outside the car or have fun doing some activities inside the car such as answering activity books or simply talking with someone.
Sit in the front seat or at least avoid being in the rear seat. The farther you are from the back, the more motion could you feel.
Get some fresh air. If possible, get rid of everything smelly in the car. Nobody should be smoking in the car or in any means transportation. You may want to open the windows from time to time to have a fresher air then just close it when you feel better.
Take naps. Eat something to make your stomach more stable and rest. Sometimes, forgetting that you're having motion sickness is really the most helpful way to get rid of it and sleeping is just one of the best ways to forget.
Take motion sickness drugs an hour or few minutes before you go.
