Utilising the number formation rhymes below you can practice at home with your child how they form their numbers correctly.
You could even print the image 4 to a page and laminate them for your child to practice with a whiteboard marker or if you do not have a laminator you could slip the piece of paper into a plastic sleeve to then use with a whiteboard marker.
To extend your child you could practice writing their teen numbers reminding them that the one gets written first and the the other number next to it on the right. I say to my class that you have to be able to run before you can do any of the other activities - eg. to write the number ten, you have to write the 1 first as the superhero first had to run before he could fly around the earth to make a zero.