Be on the lookout for signs that your baby is not hitting important milestones, like babbling, sitting unassisted, smiling, making eye contact, or responding to sounds. If you’re concerned that your baby has missed any milestone, call your pediatrician.
Play peek-a-boo and similar games with your baby. It will help teach the idea of object permanence -- that objects still exist, even when they’re out of sight.
Place toys just out of reach on the floor to encourage your baby to start crawling.
If you have older children, make sure to put away toys with tiny pieces to prevent your baby from choking.