They say they are on the rise! I've only seen on a tree farm. Do they have to be native in your zone?
They are native in NJ! And we have some BB experts with their very own forum who would love to help you.
Here is a link that might be useful: Bluebird Forum
There's a lot of ways to attract birds. Here are some information on how to attract birds. You can provide some food like seeds or grains. Give them some nesting materials, anything a bird can use to make a nest. Make a small pond, they can use that for taking a bath and lastly, plant some native plants.