The second link contains plans for a bluebird box, the third plans for a predator baffle that you will likely wish to utilize. Finally, the fourth link holds a lot of information concerning bluebirds and box placement. I encourage you to use this link, as the information I am providing to you is very basic. You will need to make other decisions based upon the topography of your land. The nest boxes should be placed about 200 to 300 feet apart.
Place boxes with a bit of common sense.
You obviously don't want a box facing a road. There are other houses you might consider for placement on your property, as well. A martin house may yield surprises or starlings. A box slightly larger than a large shoe box, with an entry hole of two and a half to three inches, can serve as a nesting site for kestrels, woodpeckers, or owls. Constructing the box of wood that has aged and weathered will make it more immediately attractive.