Finally, with all the prep done, pour out the dye(s) into plastic cups and decide what color should go where. Some people like to have bangs or streaks a seperate color, or fade from back to front or from roots to tips. I wanted a "fall leaves"/"flame" effect so we just alternated shades.
Before you start, rub petroleum jelly along your hairline: the dye will stain your face and ears if it drips or rubs, and its rather hard to remove.
Dye hair from back to front, make sure the hair is saturated, and use a fine toothed comb or stiff brush to brush the dye into the hair. Get close to the roots but dont dye the scalp: it looks wierd.
Now cover your hair with a showercap if its long to keep it from getting all over the place. Some people use a hair dryer to speed this up, but I dont. Wait 30min-1hr to get a good set.
When you wash it out, try to do it in a slop sink or similar because the dye can stain the porcelin and its a pain to get out (softscrub/ajax seems to work well). wash away from the face and body so that the dye doesnt drip onto your skin and paint it. A wand is good here. Maybe have your friend help you out. Wash until the water is clear, 10min minimum...otherwise you will just get dye on everything.
The folks at haircrazy
suggest a vinegar rinse to help set the color. this seems like a very good idea, but i didnt know at the time.