If your going to share your bed with your infant I would suggest that you place pillows around the baby. This will help in two ways. The infant will not roll out of bed and you will be less likely to roll over on your infant.
It is my opinion that the best place for a infant is in a crib. If you need to have them in the same room place the crib close to the bed. Getting the infant used to sleeping in its own bed will save you a headache later on in life.