If you are unable to keep any food down you may be having a condition called hypermesis gravidarum which needs medical intervention! So, make sure you inform the doctor about the same. Its time to quit smoking. In fact, even passive smoking must be avoided.
Exposure to chemicals around the house and at work must be limited. Avoid beauty treatments which involve chemicals or cleaning your home with strong disinfectants or acids.
Discuss all your concerns with your doctor at the first prenatal visit. Also, share your complete medical history so that your pregnancy care is planned appropriately. If you have a pet and especially a cat, avoid changing the litter box as you could contract infections which spreads through pet litter.
These early days of pregnancy are critical for your baby's development, so do not forget to take your prenatal vitamins (folic acid, iron, and calcium). It is important to consult your doctor about medications you are taking as many over-the-counter drugs aren't considered safe during pregnancy.