Biggest thing with any headlight restoration is that you've removed what UV protection the headlight had. They will cloud over again very quickly unless you protect them.
I did the S2000's headlights several times - I was always happy with the results right after, but not for long. This last time, I bought some clear headlight protector film and covered the headlights after polishing them. 18 months later and the headlights still look like new.