"You can make more friends in two months by becoming interested in other people than you can in two years by trying to get other people interested in you."

And after analyzing described real-life situations in the book, I summed up all filtered content outcome in shorts:

Part I: Fundamental Techniques in Handling People

PRINCIPLE 1 Don't criticize, condemn or complain
PRINCIPLE 2 Give honest and sincere appreciation
PRINCIPLE 3 Arouse in other person an eager want

Part II: Six Ways to Make People Like You

PRINCIPLE 1 Become genuinely interested in other people
PRINCIPLE 2 Smile
PRINCIPLE 3 Remember that a person's name is to that person the sweetest and most important sound in any language
PRINCIPLE 4 Be a good listener. Encourage others to talk about themselves
PRINCIPLE 5 Talk in terms of the other person's interests
PRINCIPLE 6 Make the other person feel important–and do it sincerely

Part III: How to Win People to Your Way of Thinking

PRINCIPLE 1 The only way to get the best of an argument is to avoid it
PRINCIPLE 2 Show respect for the other person’s opinions. Never say, “You’re wrong.”
PRINCIPLE 3 If you are wrong, admit it quickly and emphatically
PRINCIPLE 4 Begin in a friendly way.
PRINCIPLE 5 Get the other person saying “yes, yes” immediately
PRINCIPLE 6 Let the other person do a great deal of the talking
PRINCIPLE 7 Let the other person feel that the idea is his or hers
PRINCIPLE 8 Try honestly to see things from the other person’s point of view
PRINCIPLE 9 Be sympathetic with the other person’s ideas and desires
PRINCIPLE 10 Appeal to the nobler motives
PRINCIPLE 11 Dramatize your ideas
PRINCIPLE 12 Throw down a challenge

Part IV: Be a Leader: How to Change People Without Giving Offense or Arousing Resentment

PRINCIPLE 1 Begin with praise and honest appreciation
PRINCIPLE 2 Call attention to people’s mistakes indirectly
PRINCIPLE 3 Talk about your own mistakes before criticizing the other person
PRINCIPLE 4 Ask questions instead of giving direct orders
PRINCIPLE 5 Let the other person save face
PRINCIPLE 6 Praise the slightest improvement and praise every improvement of the person
PRINCIPLE 7 Give the other person a fine reputation to live up to
PRINCIPLE 8 Use encouragement. Make the fault seem easy to correct
PRINCIPLE 9 Make the other person happy about doing the thing you suggest.

Wow great