Other than helping your children grow up health and happy, the most important thing you can do is to assist in their education, especially reading skills. Speech, reading and writing are all linked; this means that teaching your child to read will undoubtedly affect their speech and writing abilities.
Encourage your child to experience and discover new things through reading. If they have a question about something, instead of telling them, point them in the direction of a book that will answer their question. This will not only encourage your child to read but also show them where they can learn new and interesting things.