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.
If wallpaper coloring can be used only within a child's room, the «coloring pages for kids» can be easily printed out and your kid can take it anywhere: outside and when visiting someone. They will be useful everywhere, the baby will not be bored, and could spend time with an advantage. If you have internet access, then the child can offer coloring online. This type of coloring will get your child interested, because they also include some tips.