Knowing your own darkness is the best method for dealing with the darknesses of other people.
— Carl Jung

Deal with the big while it is still small.
Lao Tzu dealing quote

The secret of life is honesty and fair dealing. If you can fake that, you've got it made.
— Groucho Marx

When dealing with people, remember you are not dealing with creatures of logic, but creatures of emotion.
— Dale Carnegie

The secret of man's success resides in his insight into the mood's of people, and his tact in dealing with them.
— Josiah Gilbert Holland