Welcome to the site from Sonoma County CA
My suggestion on your black paint is to look at the Poorboys World line of product..its real easy to use, will work great by hand and machine...good on the pocket book!
There are a few steps that you need to go threw...cleaning the surface of the paint...clay is that step...removing the swirls...light cut compounds are that product...polishing stage...mild polish to continue to remove swirls and smooth out the finish...that brings back the luster in the paint and then your toppers...glaze, sealant and wax...That a basic description of the process...I would start by looking up each of the process I've outlined and see what others have done and what products they used...lots of good info on this site