Graffiti is a stylistic art form that originated in the inner cities as a form of urban expression, but has since gained more widespread appeal. Graffiti art has an almost caricature feel in its form. Graffiti can be accomplished with any medium, although spray paint has always been one of the main elements of graffiti artwork. Starting with something as simple as a brick wall done graffiti style, almost anyone can learn the urban art style represented by traditional graffiti.
Choose a canvas. You can spray paint graffiti on traditional canvas or even a wall. The more space you have to work with, the more fun you can have creating your graffiti bricks.
Use a black fine-tip marker to make definitive outlines of your bricks. Use a reference photo if you like. Draw each brick outline with the black spray paint to fully outline your design before you begin. This will help add depth and definition to your graffiti art work, and help enhance the colours after they've been added. Make the bricks look fatter than real bricks, with rounded corners. This is a typical graffiti style. Paint each brick outline first, leaving about two or three inches of space in between each of them. This is the space you'll use to give the bricks dimension.
Fill the spaces in between the bricks with dark red spray paint. This will create depth. Go over the dark red with your grey spray paint, but don't apply the grey as solid as the dark red. You want to apply it in short, intermittent bursts, just to break up the solid effect of the red paint.
Apply a light red spray paint to the front face of each brick by moving your hand side to side in short strokes as you apply the spray paint unevenly, darker in some places, lighter in others. Add a layer of white over this, using the same application method, then follow up with brown spray paint applied in the same way. Continue to apply these colours until you have the worn brick appearance you're after. To give the wall a more decayed effect, apply darker patches of grey paint around the edges of several of the bricks. You can add final definition with the marker or with a fine brush dipped in black paint.