1) Eat frequent, small meals. Pregnancy sickness is much worse when you eat large quantities of food all at once, and being full-up makes you more likely to vomit as well. Instead of three times a day, try eating six times a day.
2) After a while, you will realize which foods and smells trigger your morning sickness, and then you can start avoiding them. For some, it is coffee, for others it is fish, and others are triggered by the smell of their shampoo. This is highly individual.
3) Lemon and ginger are a great herbal remedy for nausea. Whether you have motion sickness or pregnancy sickness, this combination helps a large number of people. You can try lemon and ginger fresh, sugared, or dried. There are even pills available. Many women also enjoy lemon and ginger tea to tame their nausea in the first trimester.
4) Acupuncture can help alleviate severe morning sickness. If you are one of these women who suffers from dehydration due to constant pregnancy sickness, and whose health is threatened enough to be considered for hospitalization and IV fluids (yes, it happens!), acupuncture is something you might want to try first. Traditional Asian medicine has been curing morning sickness in this manner for many hundreds of years.
5) Don't try to stop yourself from vomiting. In my personal experience, vomiting can bring you great relief from morning sickness in the first trimester. In my case, as soon as I threw up, any sign of nausea would be gone.