Sulking in needless drama. Your life already has enough drama on its own. Keep yourself from getting caught in somebody else's drama. Mind your own life and direct all your energies to making the most out of all your positive abilities. Also, don't hold in any anger or envy with in you. If something negative gets to your way, try your best not to be angry, annoyed or scared. Study the situation and know how you can turn it around for your benefit.
Seeking approval from other people. I read somewhere that you must always do your best in everything and quit chasing other people to like you or your work. The right people will come at the right time. If you have a healthy perception of yourself and of your abilities, you will understand that you can't please everybody. Stop adjusting your life or yourself to fit in another person's expectations. Live your own life and be at your best all the time.
Use of weak language. You need not brag about yourself but don't use weak language when referring to yourself or your abilities. Instead of saying 'I'm just a school teacher," say "I'm a school teacher for so and so years." Drop the just. Everybody else will look down on you if you look down on yourself.