Sand pocket-hole plugs before gluing them in place
Like most folks, I generally sand pocket-hole plugs flush with the surrounding surface after gluing them in. But some pocket-hole placements make it impossible to get to the plug with a sander. And, you risk sanding through the veneer when working with plywood. At those times, sand the plugs before gluing them in place.
First, drill a series of pocket holes into the face of a holder made from hardwood scrap. Insert a plug into each hole. Then, sand the plugs flush, being careful to not sand into the face of the holder. Push a narrow pick, such as a long-necked hex wrench, through the screwhole on the edge of the holder to free each plug. Now, insert the sanded plug into the project's pocket hole—it should sit flush, with little or no sanding required.
—Errol Koehn, Montezuma, Kan.