Find letters in pictures, signs, and other written media. Make a game of pointing to letters that begin words such "burger" which begins with the "b" sound. Remember there are few perfect letter-sound relationships, but there are general rules to help children make letter-name-sound associations.
Teaching children "The Alphabet Song" is a good step in letter awareness, but using a manipulative such as magnet letters on board, or a wooden puzzle, enriches the experience because it gives the name and the shape of the letter. Also, children can write the alphabet on a piece of paper as they sing.
Whether you write by hand or type on the computer, let the child see your writing. As you sound out words to check your spelling, let your child see you write. Also, write little messages to your child and repeatedy read it until the child reads a message such as "I love you" by herself.