Same way I took care of Nitro when I had black Show cars. High quality Carnauba based car wax. Right now am using Meguiars #26 Yellow wax. Best I ever found was a product I got at a World Of Wheels here called Beats Um All. The wax + on Black or another dark high gloss for swirl removal I use 3M Pink seal and reseal Glaze.
1993 Washburn USA MG 92 in Black Nitro using the #26