The material. Some coloring books offer the ability for the child to simply run over the surface with the pens or crayons provided, and it will turn out to be the right color regardless. Some are more like paint books, and some have magic marker surfaces and come with markers that will not show up on any surface but the specially prepared book pages. Choose the book that best suits you and your child. If you are worried about markings on the walls, then dont select a pack of basic crayons, get something that uses special crayons. If you want your child to exercise their own creativity and not have to fit in the lines or color schemes planned, get basic pages. It is up to you.
Have you ever sat back and really thought about how much fun you really do have when you are sitting down coloring with your kids? If you are like most adults you might simply shrug it off and not really pay that much attention to this; yet there quite a few adults that really embrace that creative side and decide to express it by drawing or painting as either a hobby or a profession. If you are one of the really creative people you are likely to take that next step and simply make your creative passions work for you. This is something that many people really never give that much thought to as kids; or maybe those kids that became well known artists always knew that they wanted to share their creativity with the world. It is kind of amazing when you really think about the fact that just sitting there coloring either by yourself or with your kids really can make a big difference in your life.