Use large lined paper...have students write numbers 0-9.
Making it fun. Use construction paper and pre-draw a single number such as 1 have your child cut out the number with a set of plastic scissors. Teaches visual recognition of numbers and improves eye hand coordination.
Making it natural. Using the numbers that you cut out have your child be a "7" the day. Make this a habit. Each week they are a different number. This will get them through "0-9" 5 times in a year.
Play a game. As you are driving, walking, or even watching television have your child recognize the number throughout the day. It is important at this stage that you focus on recognition.
Begin writing. Writing at this age can be rewarding or frustrating for a child. Remember that not all children develop "eye-hand" coordination at the same rate. DON'T push them if they are having difficulty handling a pencil, pen, or crayon. My first daughter had trouble and we purchased her a V.Smile video game system. She was allowed to play as much as she wanted on the weekends. Her hand strength and "eye-hand" coordination showed significant improvement in about 6 weeks. Winnie-the-Pooh was her favorite and I liked it because it helped with counting and especially number recognition.
Repeat. Change the number every week. Play recognition games. Begin writing (10 minutes a day maximum). PDF of Large Scale Numbers