Learning the alphabet--not only identifying all the letters but the sounds that each can make--is the essential learning block to language development. Teach your child the alphabet song, but also to identify the symbols with magnetic letters on the refrigerator. Have your child sort the alphabet into groups of similarly shaped letters, e.g., E, F, G, A. When secluded with close cousins, it will be easier for many children to identify the differences among letters. Buy two sets of letters and have your child match them up. Start by having him memorize capital letters; then move on to lowercase.
Reading to children is important for clear reasons, but how you read to children is also significant; certain techniques can greatly affect how preschoolers retain what they see and hear through language. Try reading stories to new readers side by side as you roll your index finger along the bottom of the sentence you're reading. This will allow children to see what they're hearing--the actual words and not just the pictures. Try reading the same book, preferably one that the child enjoys, several days in a row. Add new dimensions like props or having the child predict plot twists.
Nobody wants to read a boring book. Consult with librarians, teachers and parents for titles that strike an artistic or academic interest in you. Good books for a preschooler tend to have strong plots, simple text, recurring lines, unusual concepts, aesthetic quality and literary staying power.
Add regular opportunities to explore new roles or realities to propel language development. Arizona State University's Infant Child Research Programs gear preschooler education settings around a "dramatic play area" at the center of a classroom or play area with a theme, like instrumentation or plants, that changes on a regular basis. This keeps all children interested in a variety of subjects and vocabulary terms. Ask questions to spur responses and exaggerated replies to create a lighthearted mood--and in the process, language development, one sentence at a time.