Step1
Birth to 1 year. Books include Jamberry, I Am a Bunny, Goodnight Moon and any touch-and-feel book or nursery rhymes. Baby Einstein is a popular video series appropriate for this age, as is Gymboree, Babymugs! and So Smart. Raffi has been classic children's music for years, while classical music is said to be good for cerebral development.
Step2
For children 1-3 years old, look for items with a bit more substance. Now is when books like The Little Engine that Could or The Itsy Bitsy Spider should be read. Dr. Seuss can be introduced around this age, as can Eric Carle books like The Very Hungry Caterpillar. Anything with ABCs, numbers, shapes and colors is good. Public broadcasting has great television and video series for toddlers (Dora the Explorer, Clifford, etc.), while Winnie the Pooh, The Wiggles, Peter Rabbit and other favorites can be viewed, as well. At this age, the children still haven't grown out of Raffi, but can be opened up to the music of Barney, Country Bears and Sesame Street songs.
Step3
For 4-5 year olds, Maurice Sendak and Shel Silverstein titles can (and should) be introduced. Berenstain Bears and Make Way for Ducklings are favorites perfect for this age group. Public television is still a a life saver, while the slightly more mature content (good vs. bad) of Disney movies can be handled. Musical tastes have matured at this point, but so, too, should have your willingness to open the child up to more music. The Sound of Music soundtrack is a given, but Peter, Paul & Mary, Bob Marley and Peter and the Wolf are good tunes.
Step4
When the children are between 6 and 9 years old, the Harry Potter and Lemony Snicket series are safe. Classic titles like Madeline, Amelia Bedelia, Encyclopedia Brown and Charlotte's Web should be read. With videos and music, the children can be opened up to more pop-culture pieces in small doses. It's a judgment call for parents, but so long as there are age-appropriate themes and language, they should be acceptable. Some examples might include, the Harry Potter movies or the film The Princess Diaries, while mild radio pop is good music. However, kids are also curious at this age like they haven't been at other times. It's a good time to expose them to world music, jazz and other genres that might otherwise be tagged "grown-up."
Step5
Once a child reaches 10 years old, they can begin to explore and educate themselves a bit more. Reading, listening and viewing becomes something to think about and participate with, rather just do or entertain. J.R.R. Tolkien, C.S. Lewis and Judy Blume come into view about this age. Films rated up to PG-13 might be acceptable, even if the child is a bit younger. Again, that's a parent's personal judgment call. Find versions of pop music that might even be a bit racier, but have been edit for a younger audience. At this more independent age, it's especially important to preview books, videos and music for evaluate for language and subject matter appropriateness.