Shake the can of spray paint to properly mix the chemicals. Aim the nozzle outward and stand close to your canvas -- wall, poster board or flat wooden plank, for example. Start at the top of the "S." Press down on the nozzle and complete the top swoop of the letter. Make the swoop large and round to give it an enhanced bubble effect.
Sweep the line of paint downward and to the right in one single motion. Stop before you complete the bottom swoop. Shake the can again and go back over that single line to sharpen up the paint. Stop at anytime during the process and/or make smaller strokes to keep control over your paint.
Go back to the top and add the second part of the outline. Continue in the same bubble looping manner and stop at the same point as the first line.
Decide how you want to end your bottom swoop: thin the bubble and let it trail off; shape it off with a right angle; continue in the same looping motion. Make your decision and complete both lines of the bottom swoop. Consider making the bottom swoop slightly different than the top to add a boost of pizazz to your graffiti art.
Run short bursts of paint back and forth along selected sections on the outside of the letter. Shade in portions of the perimeter and the most extreme looping points on the letter to add definition and a three-dimensional quality.
Get creative with colors and fade if you paint in the entire surface of the letter. Choose colors that contrast with your canvas. Pick metallic or bold tones to give your letter a visual pop.