Fully Certified Detailer!!
id recommend doing the routine of washing the car properly first. its all about the prep work mate. firstly get the paint as clean as it can be. use a APC to remove and break down contaminents. wash the car i.e 2 bucket method.
use tardis or similar product to remove most of the tar, road grime etc and then use iron x which breaks down the chemicals which tardis cant do and then wash off and then clay the entire car. make sure you get everything off the paintwork as it all helps to bring clarity into the cars paint.
once clayed i would opt for a paint cleanser like dodo lime prime, apply to car and remove via instructions. this will help leave the paint in a nice clean state ready for future products. for black i would opt for poorboys black hole as this gives a nice deep finish to the cars paint(leave on for an hour for a deeper finish) but it is a wipe on wipe off product and you can do 2 coats if you wish but no need.
once buffed off you can apply either a wax or a sealant. dodo blue velvet or purple haze will be good for your car in a good price range. chemical guys blacklight sealant will be another good choice to for your car, it has nano technology so bonds to your cars surface and will protect the paint for a long time. you can leave for 15-30 mins each coat and just put around maximum of 3 coats on then you know you have good protection.
you havent got to use the products i have just mentioned as there are lots out there but i find these products work well on black/dark cars when doing things by hand