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.
Birdhouses should be placed in fall or winter, if possible. Swallows may use nest boxes set out during late May or early June, but owls, chickadees, and woodpeckers begin looking for nest sites during February, March and April. Always face the birdhouse so the entrance is protected from prevailing winds. Kestrel nest boxes should be placed at the edge of a forest area or on a post in an open area 12┰ feet above the ground.