I think the best advice I have seen on is not to worry about it. Motion sickness can usually be overcome by experience. When you are constantly thinking about getting sick, you probably will.

I found that some cool air helped me significantly. Some guys use those patches you buy at Walgreens. Again, I think it is initially physiological (you aren't used to the motion) then it becomes psychological (in your head). Most of us felt ill when performing aerobatic training or spins. Some worse than others. You will become used to it soon like the rest of us did. It will be no problem after a few more flights. Try not to be too anxious.