To keep your child engaged with reading, you should keep a wide variety of books on hand, and make sure to include books on topics that interest him. In your book collection, keep books that your child currently enjoys so he can read them over and over again (repeat readings are great they help kids feel comfortable with the story and begin "reading" it along with you!). You should also add new books regularly, and make them a little more advanced than his current collection. He will let you know probably through a lack of interest when a book is too difficult. Picture books are good because they allow you to point out words and help him begin to recognize letters and their associated sounds. Pictures also give clues to the story for young children who are just grappling with languagelearning, but if he can follow the plot of a book without pictures, that's wonderful! The important thing is to go at his pace, but maintain a rich and varied literary environment.
For more information on reading to young children, check the following section of our site:
We also have a great list of recommended books for kids by theme, award winning books, etc. that you can order directly from amazon.com through our site.