Your word is your BOND.
As we use technology more and more the one thing that will never change is be successful in life your word MUST mean something.
Both in your personal life and in business to gain trust you have to be known as a man (or woman) of your word. Nothing beats a handshake and eye contact and a promise.
You need allies , friends and relationships in order to succeed, NO ONE can do it alone.
No matter what business you are in you will need help and to have people want to work with you they need to know that what you say is exactly what you will do.
They also listen to you and if you are constantly bad mouthing others and do not back up the people around you than they have no reason to believe that you will not turn against them.
Be consistent, be honest and ALWAYS keep your word.