Step 2: Paint
Clean the surfaces. Remove any dirt, dust, or oil from the edges of the doors.
Tape off the gaskets, the latches, any screw heads, whatever else.
For a newer car, I would mask off both the outside of the door AND the inner panels to avoid overspray. This was not a newer car, so I didn't bother.
Spray on white paint as undercoat. The white helps the orange to cover and show up brightly. If you spray on orange without the white undercoat, it either looks dull, or it takes a LOT of orange.
Don't close doors. Let the white dry.
Spray orange over the white.
Don't close doors. Let the orange dry.
Pull off masking material.
Done. Doors may be closed now, and vehicle is safer.
Seems to me that putting bright paint, or perhaps reflective decals, on door edges would be an inexpensive way for car manufacturers to increase the safety of their products, in case they were so inclined. I recall seeing some car doors with safety lights on the edge, and that's an excellent idea. Especially good at night.
If this little paint job averts one mishap, it has paid off. More than.