Depends on what type of birds you want to attract. Not ALL birds use bird houses or nest boxes. I find that the best place to put a nest box is on a post or fence pole, about 4-7 feet above the ground. You can put some sort of baffle or barrier around the pole above and/or below the box to keep cats and other predators out. If you are after bluebirds
the boxes should be spaced about 300 feet from any other bluebird
nest box or any human building, for best results. Here is a picture of a typical blue bird
nest box with the critical dimensions that I drew using Google Sketch-Up:bluebird
I am Thornius, the Bird Man here. I live in Nashville, TN. Welcome to the forum!!!