I've read just about everything there is to read on morning sickness and how to prevent it. Since I have 3 children, I know this works:
As soon as your first day of morning sickness comes or approximately 8 weeks into pregnanacy, every night directly before going to bed, eat a carrot or apple w/skin or a piece of celery - anything that is extremely difficult to digest. It will last in your stomach all night.
The main cause of morning sickness is an empty stomach. If your stomach has something in it already, you will no longer, (or will never)be sick in the morning again.