Make sure children are taught the proper operation of the tool, and the safety precautions. Eye protection is a highly recommended safety precaution to take. As with any other hobby, practice will increase the enjoyment and the skill. The tip can create very a fine line, or dark shading depending upon how much pressure is applied and for how long. Practice something simple initially, perhaps writing your name on a scrap piece of wood, try to write your name with uniform dots, or lines that are darker on one side as if in shadow.
Wooden fruit crates when taken apart and sanded make excellent practice pieces.
The slats are small enough to be easily handled, but at the same time are large enough to allow your creativity to shine through. Softwoods are easier to work on since they require less pressure, and a shorter amount of time to char and create many interesting patterns. Once you are comfortable with the effects that can be created with the tool, then it is time to start building more complex and attractive items. The first step is to use a pattern and the carbon paper to trace the pattern on to the wood. Now is the time to check for alignment, and fit.