Begin with sounds your baby already shows an interest in. Imitate those sounds as use them as building blocks for sound- or word-families. Ba-ba-ba can become ca-ca-ca, da-da-da and so forth, expanding your child's sound vocabulary. Expand using the initial consonant: ba-ba-ba becomes bo-bo-bo, be-be-be and other sounds. Imitating your child or modeling mimicry of sounds in the baby's environment encourages your baby to imitate and mimic as well.
Associate sounds with objects familiar to young children, and expand them to full words. Ba-ba becomes "bottle'; the child can have the experience of asking for a bottle in manageable form ("ba ba") but also begins to absorb the tecniques of forming sounds into larger, consisent forms of meaning.
Choose reading and singing materials that will help emphasize the sound-meaning link. Nursery rhymes are often appealing to children because they rely on simple rhymes and often melody. Meaning is important but not critical for learning and fun. Few children these days know what Jack is doing when he is being "nimble." "Hickety pickety my black hen" feels good just to say. The fun of Little Miss Muffett and the repetitive quality of the Three Bears help children enjoy the predictability of rhyming.
Invent games and phonemic devices using the materials of a familiar context. A trip to the grocery store can become a search for all the food items beginning with the same letter as that of the child's first name: B is for Bobby and bread, and beets, and bologna and many other objects. Older children like nonsense rhymes even beyond the delicious prospect of having a reason to say "poopy" aloud without criticism.
Sing with your child as another way to boost phonological awareness. Being able to join in with group singing is a powerful experience which far overwhelms the embarrassment of not quite having the words straight (as the National Anthem rendered at most ball parks illustrates clearly). More than one child has sung the alphabet song for years before questioning what letter represents the elemeno.