For a healthy baby.. ...Without an additional risk factor (such as prematurity or family history of sids), sleeping on her back in a clean, smoke-free, well-ventilated room, without pillows or heavy covers, and without co-sleeping, offers the best chance for avoiding sids. Additional measures may be needed for high-risk babies.
Baby sleeps on back. The best way to prevent sids is to put your baby "back to sleep." sleeping on their back is the safest position for babies and has been demonstrated to reduce the incidence of sids by about half compared to when babies sleep on their tummies. Another important thing is to not smoke around the baby or in the house. Co-sleeping (having baby sleep in bed with you) is also associated with sids.