What is the meaning of ethical considerations?

There is no best marketing method. They all work, provided, they are all executed properly. The best marketing method is the one that works best for you. The main thing is not to fall into the trap of jumping from method to method like so many marketers do. You have to be disciplined enough to be patient. You have to give whatever method(s) you're using a reasonable chance to work. Then, when you find something that works, milk it to the point of diminishing returns.