Learn to speak politely with one another.
Say that which is good or remain silent. The devil is an enemy to man. The moment you say something impolite he will use to turn you against your Muslim brothers and them against you.
And say to My servants (that) they speak that which is best; surely the Shaitan sows dissensions among them; surely the Shaitan is an open enemy to man.
[Qur'aan 17:53]
Abu Hurairah (May Allah be pleased with him) reported:
The Prophet (sallallaahu alayhi wa sallam) said, "He who believes in Allah and the Last Day must either speak good or remain silent."
[Sahih Muslim]
This Hadith is explicit evidence that one should only speak when he has something good to say. Otherwise, he should remain silent. Good speech is that which brings about benefit. If one doubts that what one has to say will bring about good then he should remain silent.
Narrated Abu Huraira:
The Prophet; said, "A slave (of Allah) may utter a word which pleases Allah without giving it much importance, and because of that Allah will raise him to degrees (of reward): a slave (of Allah) may utter a word (carelessly) which displeases Allah without thinking of its gravity and because of that he will be thrown into the Hell-Fire
."
[Sahih al-Bukhari Hadith No. 6478]
Remember, what you say is a slave to you as long as you have not said it. Once you have uttered it, you are a slave to it. Choose wisely what you want to enslave yourself to.