Create thumbnail sketches to help you decide on a layout. Choose the image that has the most punch and best composition to be your final image. Mark out the basic design for your graffiti image with a black marker first. This will give your drawings a bold and crisp outline. Give letters a bubble-like look, and all your figures should have a slightly baggy appearance near the bottom.
Fill in the basic colors inside the black marker lines. Be sure to choose bold colors so that your graffiti illustration pops. Use complementary colors within your drawing. Balance cool colors like green, blue and purple with warm colors like red, orange and yellow. This will make your image visually interesting.
Add shadows to give your piece a three-dimensional look. Choose marker colors that are a few shades darker than the base colors you have already put into the illustration. For example, if you are adding shadows to a green hat, use a darker green marker for the shadows. A quick way to place the shadows is to add a dark band of color to the bottom of each object such as the bottom of a hat, under the nose of a character, under the chin, arms, or the bottom of the shirt. The same technique can be applied to graffiti-style letters.