If, however, you need to attract some attention or are participating in a motorsport that would benefit from you making a scene, there's only 8 steps, that's not many steps.
These steps are for a removable body panel but they work the same for anywhere on the car (it's just a little more comfortable to be painting indoors).
2" Masking or painter's tape
X-Acto Knife (new blades, watch your little piggies)
Spray paint (I used Montana, quality paint, quality tips...less swearing)
Oil Based Sharpie Paint Markers
Step 1: Masking the Area
Cover the area you intend to work on with a large amount of masking tape. It gives you a surface to draw on (especially if the actual surface is a dark colour), it also acts as a stencil once you start to paint.
The iced coffee is optional but recommended.
Step 2: Drawing the Image
I generally do things freehand but you have the option of using an overhead projector to blow up a smaller image or to give you an image to trace.
Once you're happy(ish) with the image, it's knife time.
(The image is faint, but everything will be clear in the next couple of steps)
Step 3: Cutting the Stencil
Using a sharp knife, begin cutting out portions of your image. Anything that is going to be the same colour should be cut out at the same time.
Step 4: Painting!
Spray well taking care to not overload the surface with paint (avoid the runs, no one likes the runs).
Make sure the paint is no longer tacky to the touch before you mask off the painted portions to start on a new colour.
Step 5: More Different Painting!
Paint all the sections!
Step 6: Outline and Detail
All your blocks of colour have uneven gaps between them. They'll be floating waiting for everything to be tied together. Luckily, you have your black Sharpie ready to go.
Start outlining. The paint marker can be messy, keep your hands up and off the marker. Smudges are a pain.
Step 7: You Did It! Geez, What Did You Do?
Sign your masterpiece!
(It should be noted that there are spots of bondo and primer on this hood from unrelated work, because drift car)