This is a simple setup and technique that will render amazing results. You can choose to do just light graffiti with the instructions provided or just a portrait. Feel free to comment with a pic of your results.
Step 1: Materials
SLR or DSLR camera
Finger lights (dollar store, toy store, and some gumball machines) (see image)
A model or self
Chair or stool (I used a car in a garage for mine, model sat on hood of car)
A room with no windows (garage)
Step 2: Camera Settings and Techniques
F-stop : f/5.6
Shutter speed: 20 seconds
Focal Length: 18mm
With the lights on in the room, set up your shot with camera on tripod and have model practice pose, it has to be held for 20 seconds. Do your focusing manually with room lights on and leave the lens set on manual. Practice with your hand where you will be sweeping the finger lights and what patterns you will be forming. You will want to follow the curves and natural lines of your model, so you don't bump them. Also, give yourself space to work behind your model. I recommend the photographer wear black when taking pictures and to move quickly. I would recommend drawing light graffiti for 10 seconds and washing the model with light from the finger lights for 10 seconds. This will be the only light that will grace your model.
So, once focused, practiced and model in place, turn off the room lights, turn on your finger lights. Press shutter, move quickly around model to graffiti and then wash model with light.
See sample images.
Step 3: Troubleshooting for Better Results.
Make sure finger lights face lens to get sharpest graffiti. Remember to point finger lights on to model to wash with light, no doing so will leave dark areas. Use finger lights in a panning motion multiple times and tuck into hand when done. Switch up colors when panning for various effects. Do not point lights on anything you do not want in the picture, items in background may be visible in final photo if you do so. Do not stand still behind subject while doing light graffiti, you may be visible in picture. Make sure model can keep pose. See sample images.
That's pretty much it! Have a blast!