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.
To make a max benefit from coloring cheerful pictures, it is desirable to get involved as well. At the same time you should give maximum freedom for actions to promote and in any case not scold if the baby suddenly wants to use a non-standard approach to the application of paints and colors. Let your kid color the alligator in red and swan in green; you shouldn’t blame your child for using the wrong colors, but try to turn it into a fun story. This type of activity should encourage the child to the creative process and the knowledge of the new information, while the parents should contribute to this in every way.