While sanding my Master Chief helmet I noticed I was making a few small holes in certain areas. What should I be doing differently to avoid this? I started with 80, then bumped up to 120 then stopped when I noticed them. Is this salvageable? What would you recommend for filling in those holes?

While sanding my Master Chief helmet I noticed I was making a few small holes in certain areas. What should I be doing differently to avoid this? I started with 80, then bumped up to 120 then stopped when I noticed them. Is this salvageable? What would you recommend for filling in those holes?