The picture should be large without small details, images must be recognizable, kind and interesting, for kids contour lines should be thick, it hides some errors made by child, the outlines of the pictures should be smooth, without corners, difficult bends.

You should pick soft triquetrous pencils for a small kid. It is sufficient to have a set of six basic colors. When coloring, try pronouncing the name of each color, this helps the baby to remember them.

Bambi The Book