Dale Carnegie's "How to Win Friends and Influence People" is a fantastic resource that has been read by millions of people. However, for those of you who do not have the time to sit and read, listen to yet-another-Audible-book, or CliffsNotes from Blinkist, here is another resource.
Before you say anything to anyone, ask yourself three things:
a. Is it True?
b. Is it Kind?
c. Is it Necessary?
Make promises sparingly and keep them faithfully.
Never miss the opportunity to compliment or to say something encouraging to someone.
Refuse to talk negatively about others; don't gossip, and don't listen to gossip.
Have a forgiving view of people. Believe that most people are doing the best they can.
Keep an open mind; discuss, but don't argue. (It is possible to disagree without being disagreeable.)
Forget about counting to 10. Count to 1,000 before doing or saying anything that could make matters worse.
Let your virtues speak for themselves.
If someone criticizes you, see if there's any trust in what he says; if so, make changes. If there is no truth to the criticism, ignore it and live so that no one will believe the negative remark.
Cultivate your sense of humor; laughter is the shortest distance between two people.
"Do not seek so much to be consoled, as to console; do not seek so much to be understood, as to understand; do not seek so much to be loved, as to love."