Add color to fill in your drawing. You can use colored pencil, marker or crayon. Again, it's a good idea to look at examples before doing this, but really you can do anything you want. A very simple graffito (the term for a single work of graffiti) can have only one color. You can also easily do each letter in a different color or make the added details a different color than the letters. While you might be tempted to go crazy with color, sometimes simplicity is best. Graffiti artists traditionally had to work secretly for fear of getting caught--many still do--and so they could carry only one or two different colors of spray paint at a time--a lot of very good graffiti is just one color.