Mike, I start out with those wet/dry sanding sticks from Squadron. I Use the course grit for the tough areas and then use the medium grit to soften those areas afterwards. If I can use the medium grit stick in the first place I'll do that instead.
After everything is filled and sanded I'll use a polishing kit that has the 3200, 3600, 4000, 6000, 8000 and 12,000 sheets to get it really smooth.