Infants are attentive to the rise and fall in the rhythm of their mother's voice from a young age; provide infants with poetry recordings that display simple rhythms and ensure that the recordings are age-appropriate for infants. You can also read to the infants from a poetry book when you are available as they will be more accustomed to your own voice, which will encourage language development in young infants.
Read books to infants that make good use of pictures and a short story with simple rhythms. Whilst reading the book to the infant, point to the pictures to help the infant associate words and sounds with vibrant images and colors. Reading and showing infants relevant pictures will help develop important cognitive skills --- such as classification and attention maintenance --- and help establish important language development skills.
Purchase toys, such as building blocks or shapes, that will encourage your infant to grasp and move objects around. By 3 months old, infants will begin to notice their own hands and feet and grasp objects; they will also begin to reach for their favorite toys or colors. Encourage infants to develop their motor skills by either moving their hands and feet in motions that will become familiar to them --- you could move an infant's legs in a peddling motion to imitate riding a bike --- and guide infants with building blocks or playing with their toys.
Play music that is associated with a particular activity, or sing simple rhymes to the infant. Infants are more alert to rhythm and sounds. By playing music or creating rhymes around an activity, such as bathing, the infant will learn to associate sound and rhyme with the activity and begin to develop a basic sense of concept, such as what "bath time" is. Pictures, recordings or bath toys, such as a toy whale, can also be used.