I too have Silver paint and it is almost flawless. This is how I have done it for years.
1. Wash with P21S Total Wash. Rinse thoroughly.
2. With a bucket of warm water and super suddsy P21S Shampoo I soap up a panel and then use the clay. I do the whole car this way. Then rinse thoroughly.
3. Wash one more time, again with a fresh bucket of T21S Total Wash. Then dry it.
4. Tape all the black off with blue painters tape.
5. Polish with P21S Paintwork Cleaner
6. Lastley, I was with P21S Concours Wax. This is not my daily driver so I use the P21S. For my X5 which is a daily driver I use One Grand Blitz Wax which lasts a long time.
I can to this entire process in about 5-6 hours (I take my time and pay attention to details)