There are many different kinds of people in this world. It is very hard to find a common rule to treat the others. But you should have some basic principles to follow.
This first one is that we should always speak and act out of good intentions. When we speak or act, we should have the best interest of the others in our heart. We should never hurt or please the others for our own gains. What we say or do should be for promoting another person’s long-term wellbeing. Sometimes we should let another person know the painful truth if it will help them in the long run. But what we speak or do should be truthful, wise and gentle. When you are mindful with your speech and action, people will respect you.