Questions I must answer before speaking up / correcting someone:
1. Do I thoroughly practice what I’m about to preach?
2. Do I even preach what I’m about to preach?
3. Am I speaking up because I really want to help, or is it because I’m angry, or because I want to be on record as being right?
4. Do I actually know what I’m talking about here, or is this a situation where I and others would both be better served if I listened and learned?
5. Am I skilled enough in the means and methods of conducting this particular type of discussion to correct someone without being misunderstood?
Things I must do to properly speak up / correct someone:
1. Speak at the right time
2. Speak using facts, not opinions or assumptions, to support my point
3. Speak as gently as possible
4. Make sure that the words I’m speaking will actually help the situation
5. Make sure that my inward motivation for speaking is kind, never malicious.
[Courtesy of the Buddhist “Eightfold Path” of Being Awesome / Seeking Enlightenment, one -fold of which is “right speech”, contained in which are these lessons for when it is OK for someone attempting to not be a shithead to correct someone else (direct quote follows):
 “Am I one who practices purity in bodily action, flawless and untainted…?
 “Am I one who practices purity in speech, flawless and untainted…?
 “Is the heart of goodwill, free from malice, established in me towards fellow-farers in the holy life…?
 “Am I or am I not one who has heard much, who bears in mind what he has heard, who stores up what he has heard? Those teachings which are good alike in their beginning, middle, and ending, proclaiming perfectly the spirit and the letter of the utterly purified holy life — have such teachings been much heard by me, borne in mind, practiced in speech, pondered in the heart and rightly penetrated by insight…?
 “Are the Patimokkhas [rules of conduct for monks and nuns] in full thoroughly learned by heart, well-analyzed with thorough knowledge of their meanings, clearly divided sutta by sutta and known in minute detail by me…?
“These five conditions must be investigated in himself.”
“And what other five conditions must be established in himself?
 “Do I speak at the right time, or not?
 “Do I speak of facts, or not?
 “Do I speak gently or harshly?
 “Do I speak profitable words or not?
 “Do I speak with a kindly heart, or inwardly malicious?
“O bhikkhus, these five conditions are to be investigated in himself and the latter five established in himself by a bhikkhu who desires to admonish another.”]