The key to Black is a damn good polish to restore gloss and remove any defects. The polishing stage creates 90% of the overall looks.
Personally my chosen routes on my old Clio where:
Wash - Duragloss 901
Clay - Anything non agressive
Machine Polish as needed with Menzerna Intensive Polish and/or just with Final Finish to remove defects and restore gloss.
Prep paint for Sealant with Autoglym Super Resin Polish
Seal with Autoglym Extra Gloss Protection or Jeffs Acylic Jett Trigger
Wax - Victoria Concours or Swisswax Onyx depending on budget, or Swissvax Best of Show if money is not an issue
If no access to a machine polisher use some Menzerna PO91L by hand and then use the SRP.
If you don't need long lasting durability and just want out and out looks, ditch the SRP and EGP/Jeffs and use a nice pre wax cleaner or Glaze and go straight to wax
Wash - Duragloss 901
Clay - Anything non agressive
Machine Polish as needed with Menzerna Intensive Polish and/or Final Finish to refine and add gloss.
Prep paint for wax, Swissvax Cleaner Fluid, Clearkote Vannilla Moose Glaze or Meguiars #7 Shoe car Glaze
Wax - Victoria Concours (under £20) or Swisswax Onyx (Under £50) depending on budget, or Swissvax Best of Show (£100 plus) the later two will not add much over the Vics in looks, but the durability will be much greater.