I wet sand with 80 grit wet/dry sheet folded in thirds. You have to keep the bottom wet with running water and rinse the paper often. The paint turns to a milk like slurry as you sand. There is no need for a dust mask but keeping yourself rinsed off as you go is necessary.

I always get a kick out of seeing some guy/girl dry sanding a bottom who has turned blue/red with dust and sweat.