There wasn't a time that can be thought of when graffiti was ever appreciated as art, rather being defined as a form of barbaric behavior. Maybe it was misbehavior in its own right, but it sure was good looking. Here's the cool part about what followed the old idea of graffiti...
Done mainly with the use of LED lights or flashlights, and a digital camera with manual settings, the outcome of light graffiti, or light painting as it is occasionally called, could be spectacular if you want it to be.
What's even more fun is that anything can be used as a medium for this form of "light doodling". If it seems hard to believe, you should check out how to draw graffiti in Photoshop along with other tips and tricks.
◆ Begin by gathering up all the material / equipment that you need at a convenient distance around you. You will need it like that in order to be able to move swiftly when attempting to create the light graffiti. Make sure you have everything (basically, the lights and your camera).
◆ The next thing you want to do is fix your camera settings that will be best suited for this job. What's recommended for this is a camera with long exposure, an ISO setting of 100, and an aperture set to the smallest setting possible on the camera.
Also, for its full effect, the best recommended shutter speed should preferably be anything between 5 seconds to 30 seconds. If situations permit it, you could also use an ISO of 200 or more. You will have to use your discretion for that though.
◆ Now that you have your camera fixed to the required setting, get ready to create some magical illumination. Do not forget though, to keep the flash of the camera off, as also to work in a dark or extremely poorly lit room. Working in a room with poor lighting will allow you the complete effect of what you are trying to achieve.
◆ Most of what you need to do while preparing to do light graffiti has been covered. It is now time to head to moving in front of the camera with the lights, while creating an image / word or whatever it is that you are aiming at.
While there is no real tip that can be offered to get it right, the one suggestion that can be offered is that of practice. Also, do not hesitate to use a variety of lights, such as glow sticks (use varied sizes & colors) in order to achieve an array of looks for your graffiti.
Also, to add to the aesthetic value of what you are doing, feel free to use any good looking element available in the background. Oh, and don't forget... When writing, make sure you do it backwards so that it looks right when you get a picture of it.
All right then, what's keeping you from it? Go get experimental, keep at it with some practice, and there should be no problem with getting to a point of perfection for some fabulous light graffiti.