...be aware of the impact of your words on others you encounter and/or interact with. This story sums it up well:
Early in my career, I was collaborating with a senior colleague to write a research grant. As we discussed previous research, I was particularly critical of other researchers. My colleague, who was also an early mentor in other aspects of my life, brought an abrupt end to my comments. In a supportive but rather blunt way, he simply said, “There are two types of people, those who contribute and those who detract. You must learn that the best way to build your career and your life is through your own achievements, not by attacking the achievements of others. People will always remember what type of person you are, and they will trust or distrust you accordingly.”
Seldom have I heard words that were truer or more genuinely wise. People who have only criticism to offer are soon forgotten—those who contribute in a constructive way become part of history.