The greatest damage you can bring to yourself is by breaking the trust of others in you.
If you are trusted, you are the most successful person on earth. Be trust-worthy and value your words. You cannot be trust-worthy if you are gripped by selfishness. People unknowingly respect the person who is selfless and thinks impartially. Selflessness builds a great amount of trust. Be ready to sacrifice the little things in life for the greatest virtue of trust and self-worth.
Never divulge the secret of someone if that is harmful to him/her. And never use the secrets of someone as a weapon to harm or bend him/her. A one-time win will rob you of a life-long win. Do not go for short term benefits.
It is essential in life to make People believe that you are impartial, sincere, truthful, honest and a man of words. It needs a little more sacrifice and a little more kindness of heart. Go for it.
Do not simply use words to construct your Self-image. You may fall in the ill-habit of Self-praise. Do not speak in words, speak in your actions. Words work on the surface but actions sow seeds in the soul. Work hard on what you want to be.
Often we speak high of ourselves and expect others to believe so. But people do not go with words. People unconsciously evaluate your actions and draw their opinions of you. So speak through your acts and deeds. Think and do what you want to be. And build a concrete self image by your actions.
Many times you may not get the expected results instantly but constantly sending out the message of your true self-worth by your actions in the desired direction will one day land you on success. Have patience and stride on.