Many people mistakenly believe that they can change other people, but in most instances all they accomplish is alienating them.
This is the first course of action I would take before making any suggestion that the other person change.
Perhaps I need to change to better accept the person and try to understand why they do what is objectionable. I need to examine closely the reasons which are behind their actions. I may want to look at myself to determine if I am being too judgmental.
I certainly want to evaluate a friendship for example, so I can determine if any change I can make will be worth the effort to keep the friendship alive. Most often it will!