From personal experience with a black car; my '99 M Rdstr is Cosmos Black, and as you already know, shows the most minute of scratches. I was actually considering getting the car repainted when I decided to see what Meguiar's Scratch-X would do.
Scratch-X is rubbed into the paint by hand, and working perpendicular to the scratch(es), not in-line with them. Working on a single scratch at a time, then using a simple polish and wax procedure as each panel was finished, I was genuinely astounded by the results. I credited that tube of Meguiar's Scratch-X with saving me a__then__$2500.00!
Some years later, the car was hit in the rear corner by a drunk__pointed in the direction of the liquor store__while parked in a lot, which resulted in an all-over respray, but the simple act of removing the offending scratches bought me several years (while the cost of a respray climbed ever higher...).
Nowadays, I too use some pretty sophisticated polishes and machines, but don't rule out a short term fix on your own. Start with a small, less obvious area and gauge your results; if you're satisfied, then move on to the more obvious flaws.
Above all, read the instructions for whatever product(s) you use, work in small areas__as already mentioned__and set realistic goals. While the results will fall short of Villa d'Este judging standards, you can still be proud to show it off. Good luck!