I went for a green (light cutting / heavy polishing) and a blue (finishing) pad. The paint on RR's is supposed to be medium hardness so I thought it best to start with the blue and then try the green if needed. My car's paint is very good; if there were more swirls etc. I'd have got an orange pad I think. If you Google "Chemical Guys Hex-Logic pads" the colours are all explained.
I must say this whole detailing malarkey is a subject in itself with lots to learn. The Detailing World website is a real eye opener - a geek's paradise!