The goal of your talk should be good and beneficial
Talk can be dangerous. So, we should control it within the limits of Islam, guided by Allah (S.W.T.) and his Messenger Mohammed (S.A.W.).

The goal of your talk should be good and beneficial. If you cannot intend to have a good talk, then you should remain silent and that is good by itself. This is because the Prophet (S.A.W.) says reported by Imam Bukhari and Muslim,

"Whosoever believes in Allah and the Last Day, let him say good or remain silent."

Refrain from swearing unless it is necessary. Allah (S.W.T.) says in Surat Al-Baqarah, (Verse 224), what can be translated as,

"And do not make Allah’s (Name) an excuse in you oaths."

Talk only within your knowledge and expertise, and do not talk about what you do not know. Allah (S.W.T.) says in Surat Al-Isra’a, (Verse 36), what can be translated as,

"And do not follow (say) that of which you have no knowledge."

Do not talk to people about everything you hear without investigation and confirmation, because you may hear from others the truthfulness and falsehood and what is true and what is doubtful. If you talk about everything you hear, you will be sharing the sins. The prophet (S.A.W.) warns us in an authentic hadith,

"It is enough sin a person commits when he talks about everything he hears."

Make sure that the goal from your talk and conversation with others is to reach the truth, and reveal the falsehood. And do not be concerned whether the truth is reached and falsehood is revealed by you or by others.

Those who talk uselessly-and those who put down others-shows off when they talk
Make your talk clear, simple, devoid of words that are difficult to understand, devoid of eloquency when it is not necessary, and devoid of anything that puts down others because the prophet (S.A.W.) hates this kind of talk. The prophet (S.A.W.) says in a fair hadith reported by Imam At-tirmithi,

"The people whom I hate the most and who are the farthest from me on the Day of Judgment are those who talk uselessly, and those who put down others, and those who shows off when they talk."

Make your talk calm, clear, audible and understood by others. The prophet (S.A.W.) used to repeat the word three times to make sure that it is understood and his talk was simple that everyone can understand. Be serious in your talk and do not joke much, and if you joke, be truthful like the prophet (S.A.W.) used to do.

Do not interrupt another person when he talks and listen to what he has to say till he finishes his point, then follow up on what he said with what is good and beneficial if the follow-up is necessary or useful, not just because you want to talk aimlessly.

Talk -Devoid of harming, hurting, putting down, and making fun of others.
Talk and debate in a nice way which is devoid of harming, hurting, putting down, and making fun of others. This good way of talk was commanded by all messengers. Allah (S.W.T.) said to Mousa and his brother Haroun, when he sent them to Pharaoh in Surat Taha, (Verse 44),

"And speak to him (Pharaoh) mildly, perhaps he may accept admoition or fear Allah."

So, you are not better than Mousa and Haroun nor that person you are talking to is worse than Pharaoh.

Do not reject everything others have said if you have noticed a mixture of right and wrong or a mixture of truth and falsehood, because right should not be rejected even if it is said along with some other things that are independently wrong. Truth should not be rejected if it is said along with some other things that are independently false. You should accept the right and the truth and reject only the wrong and falsehood, and this is the justice and fairness that Allah (S.W.T.) commanded us to do.

Do not complement yourself and pat yourself
Do not complement yourself and pat yourself on the back in front of people, because usually this is a result of arrogance which Allah (S.W.T.) forbade us from in Surat An-Najm, (Verse 32), what can be translated as,

"Do not complement yourself, He (Allah) knows best of those who are pious."

Refrain from being involved in useless arguments
Refrain from being involved in useless arguments which sole purpose is to put down and prevail over others. Because being aimlessly argumentative is from the signs of misguidance (We seek refuge with Allah from it).

For this reason, the prophet (S.A.W.) warned us in an authentic hadith reported by Imam At-trimithi,

"A people did not get misguided after Allah had guided them, but they were aimlessly argumentative."

Abandon useless arguments even if the truth is on your side to prevent useless argument-full conversation.

The prophet (S.A.W.) says in another authentic hadith reported by Imam Abu-Dawud,

"I guarantee a house in the surroundings of Paradise for the one who stopped being aimlessly argumentative even if he is right."