Songs are an excellent way to teach your baby different concepts. From a very young age, you can hold your baby and dance with her while you sing the alphabet song. As your baby gets a bit older, she may want to dance, sing and clap her hands, too.
Show your baby a letter of the alphabet and make the sound that goes with it. After saying the sound normally, you can also do it in other ways--loud, soft, high and low, for example. Encourage your baby to repeat the sounds after you. This also helps your baby learn how to speak new sounds when he is just learning to speak.
Try to have different toys that feature the ABCs. These could be foam shapes, puzzles, blocks with letters or ABC books. As your baby plays with them, point out the letter that she's holding and ask, "What's that letter?" Then, tell her the letter that it is. As she gets older, she'll start to be able to answer your question.
Babies are rapidly expanding their vocabularies, so you can take advantage of this by labeling the items around your house, particularly the ones that your baby is most interested in. For example, you could label the bath, a chair, the table and blocks. Go around the house with your baby and point out these labels, moving your finger under the word to show how you read it. You can also point out each letter, saying, "B-A-T-H spells bath."
Foam alphabet letters are a great toy to bring into the bath tub. They quickly dry and they stick to the walls. During bath time, play games with these letters. For example, you could simply pick out a letter and say the letter, make words on the wall or ask your child to find a certain letter.
Even a walk around town can be a way to teach your baby about the alphabet. Point out the letters that you see on signs. Then, challenge your baby to find the same letters. You can also choose a letter and ask your child to find an object that starts with that letter.