With some extra time I had this evening, I began the process of preparing some of the lines of blind rivets on the top forward fuselage for paint. A few months ago, I'd hastily slapped some filler on these rivets and quickly sanded them, knowing I'd revisit them later.
1. First, I masked off the area around the rivets with blue tape to keep the sanding localized.
2. Used a 220-grit sanding block to sand the rivets and the area around them in order to remove as much of the filler around the head of each rivet as possible.
3. Vacuumed and cleaned up the sanded area with acetone.
4. Primed the area with self-etching primer
This process seemed to work pretty well, and it appears it will work well of the remainder of the areas.