Send me a picture of your kid and I'll draw him. This shows a step-by-step demonstration starting with the photographs, then the first sketches, to the final cartoony version. Start by just sketching from the photo, sort, of realistic, to get warmed up, and to know the subject. Next step, try to cartoon-ize a little, caricature as you go. Layout out your final composition with light blue pencil, adding, details in order of importance. Before applying the marker color remember to erase most of the pencil so as to avoid smearing.