Have the courage and conviction to make decisions that you STICK to, never give advice that you haven`t followed yourself. And don`t try to mend other peoples mistakes, thats for THEM to sort out not you. Also don`t admit or accept blame for other peoples errors or stupidity just to placate them, STICK UP FOR YOURSELF. Know when something is broken beyond repair and have the wisdom to throw it out and move on.
And know when to stay silent, sometimes silence is the most powerful thing you can say.