Remove the doors from their tracks and move them to a well-ventilated workspace. Many people find it easier to paint doors if they are laid horizontally on a worktable or saw horses. Horizontal painting also guards against drips and runs from overspray.
Remove lacquer from the brass frames with lacquer thinner. Use steel wool to scrape off softened lacquer. Steel wool also gives the metal a light scratch that paint can easily adhere to.
Clean any remaining film and debris with a clean cloth, slightly dampened with lacquer thinner. Make sure the mirror is clean, then apply newspaper and painter's tape to protect it from paint overspray.
Prime with a spray primer for superior paint adhesion and even topcoat performance. Hold the can about 8 to 12 inches from the surface and spray, constantly moving the can to avoid drips and runs from excess paint. Apply many thin coats rather than a few thick coats. Allow to dry according to the product instructions.
Apply the top coat with a spray enamel, holding the can and spraying in the same manner as you did the primer. Allow it to dry overnight, then rehang the doors.