Hi flipper, You didn’t say what your surroundings are like. You will want to locate your birdhouse about 5-6 feet off the ground on a slick metal or pvc pole. in an open area away from fences, shrubs and trees, with a baffle to keep out predator’s. Do not mount the nestbox on a wooden pole of on a fence.
If you have not done so already, you should visit http://www.sialis.org for a lot of good information on bluebirds and how to keep predators away. The European House sparrow is one of the most dangerous birds for the blues. Since they are not native to the US you can use various means to trap or otherwise eliminate them as a danger to your nestbox. Do not let them build a nest. I just keep taking their building material out of the box if They try to build in my nestbox.
There are a lot of good people here on the forum who will also offer a lot of good information. Our season will start soon. Keep us posted on your progress.