Start by applying masking tape to cover the main areas of the body where the darker color will be applied later. Don't worry about covering the smaller areas yet.
To mask off the smaller, more complicated areas, we'll use liquid masking. This is available at most hobby shops and online.
Use the liquid masking to fill in the smaller areas, such as along chrome trim as you see here on the rear quarter panel. You'll also notice that I've applied the liquid masking to cover seams in the masking tape to avoid any bleed-through.
Here the first color coat has been applied and the masking material removed. Again, be sure to let the paint cure before removing the masking.
Next, use the same process to carefully cover the first color.
Here's the second color applied, cured and masking material removed The rough edges where the two colors meet will later be covered with chrome foil.