Doing a letterbox marketing campaign while not rocket science, you need to pay attention to various factors that may affect your results. One of the key thing one must not over look is how much demographics affects the outcome. It is important to plan your campaign and target the right area before doing any massive canvasing. Ask your distribution company for demographics information as they should be able to provide you with a breakdown you chosen area.
Remember to test test test, do not rely on one bad results