I assume you sprayed gelcoat? If so, I start with 220 wet sanding. You want to remove the orange peel with the 220. To see if you've removed it, dry the section you are working on with a towel and look for shiny spots at an angle to the light. If you see tiny shiny spots, you haven't removed all of the rough surface...keep going with the 220. Now graduate to 400 then 600. Then buff with a rubbing compound followed by wax.