Just to be clear with sandpaper (we never know), lower the number is, rougher is the sandpaper.
Usually for in modeling hobby, we use 500 then 1000 then 2000 to have a very polished surface, and apply the painting after that.
In your case if you think you have too much paint, you shouldn't go with 1000 (1000 or higher are generally made for the finish (before and after applying some coatting))