well you DO know black is the hardest color to make look good...
basically you need to eliminate scratches, microscopic and tiny ones that dull the reflection.
wash, wipe, clay bar, sealer, glaze...and buff the beejebus out of about 10 coats o wax. well not really 10 coats, a couple will do if the earlier prep work is up to snuff.
of course then you will live in fear of dust, pollen, pooping birds, stone chips, acid rain, kids with grubby greasy lil fingers, etc etc
I spent years in the car show world, and learned pretty well how to make even dark green or black cars look great...until I realized that the obsession with shine interfered with actually using a car for fun. chasing the perfect finish is a very slippery slope...the more you work toward perfect shine the farther away from it you realize you actually are. sounds weird, but ask car show ppl and they'll commiserate on this.
so then I switched to lighter color cars --light yellow, silver, light metallic blue, WRB and now white, and just have fun drivin. wash n wax occasionally and just don't worry if finish ain't perfect.
stone chips are not problems, they are badges of backroad adventures well won.