That's pretty much all there is to it, except for displaying and enjoying your birdhouses. I don't keep my outdoors all winter, just to keep them from freezing and fading. They should last several years, but the more wear they get, the more they wear out. Go figure.
At the end of the season, clean out the old nest material and store your birdhouses in a dry spot in the garage or basement, to enjoy again next year.