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.
Most birds that can be attracted to feeders are insect or seed eaters. Insect_eating species, such as chickadees and woodpeckers, are attracted by animal fats or "suet." This can be obtained from the grocery store or trimmed from beef, pork, moose, caribou, or other wild meat. Fats that have a low water content are best in areas with severe cold, because they freeze at lower temperatures. Peanut butter, another fat, also attracts birds to feeders. Its sticky consistency occasionally causes problems for birds, so it should be mixed with melted animal fat and cornmeal or rolled oats. That expensive peanut butter will last longer if it is mixed with other ingredients, anyway.