I am not a pro.
We started with 1000 grit and progressed through 1500 and finally 2000 grit. Then, the surface was carefully power-buffed with a buffing compound. The final step (done later) was to polish with a hand glaze (some people used a good carnuba wax).
Do this color sanding within 1-2 days after spraying (read paint sheet(s)). This paint gets quite hard very quickly.
