This is not talking about your child's ability to express him/herself through writing. This is talking about your child's ability to pick up a pencil and form letters.
Writing is a fine motor skill. There are things you can to do help your child develop the fine motor skills he/she will need to be able to write one day.
As messy as this sound, allow your child to play with his/her fingers. For example, allow your child to draw pictures, play with, or write letters in the sand, with finger paint, or in shaving cream (pour some on the table and let him explore).
Knowing shapes helps children know how to write letters. Drawing circles and straight lines are used all the time in letters.
Make shapes with play dough. Talk about the different shapes.
As soon as a child can hold a pencil or crayon and put it to paper, allow him/her to do so (with parent supervision with the very young ones, of course). Discuss what they drew. Allow the child to tell you what he or she draw. Praise his/her efforts. Allow your child to be comfortable with writing, no matter how imperfectly he/she writes. Avoid discouraging him/her from writing by being critical of what they write or draw.
Go outside and allow your child to draw with sidewalk chalk.
Sing fingerplay songs with your child. Allow them to practice the best they know how. Songs like "Where is Thumbkin," "Five Little Monkeys," "The Wheels on the Bus," and "Eensy, Weensy Spider."
