1.   If not to be covered by carpeting, fill with the appropriate shade of wood filler or wood plugs.

2.   Fill small holes with wood filler in a matching colour.

3.   Another man suggested to countersink the nails, seal with a sealer, fill the holes with wood filler, and repaint.

4.   Apply a wood filler to open-grained hardwoods, like oak.

5.   As for future filling of holes, use an exterior wood filler.

6.   A. Fill the holes with wood filler.

7.   A. For the holes in the treads, use a wood filler.

8.   A. It is probably not caulking, but rather wood filler or spackling compound, which is hard and should not be used to fill gaps between the boards.

9.   A. You can fill those holes with an epoxy wood filler or something like Bondo, a two-part filler.

10.   Consider filling that dowel end with wood filler before sanding and finishing.