Be sure young birds will be able to leave the nest. Roughen the inside of the nest box below the entrance hole or attach a sheet of 1ǚ_inch galvanized wire mesh, so fledging young can climb out easily. Provide woodpeckers, waterfowl, and owls with nest material. Many cavity_nesting birds will add their own nest material, but the woodpeckers, waterfowl and owls prefer nest boxes with 2ι inches of dry sawdust or woodchips in the bottom.
Use galvanized nails, as these will not rust. Birdhouses need not be painted, but the box may last longer if you paint the outside. Never paint the inside of a birdhouse. If you paint the outside, use dull (not bright or glossy) colors that blend in with the surroundings. Nest boxes that don't match the vegetation may be easier for predators to find.