Mu’adh bin Jabal reported the Prophet’s advice to him and said: the Messenger of Allah (SAW) said: “Fear Allah wheresoever you may be, and follow up and evil deed with a good one, it will efface it (the evil deed). And deal with mankind with good manners.” 
This hadeeth is one of the Forty Ahadith of the author, may Allah have mercy upon him, and in it is that the Prophet(SAW) gave three great and important pieces of advice:
THE FIRST: He said, “have taqwa of Allah wheresoever you may be.”
Taqwa means to stay away from the forbidden matters and to enact the obligatory matters – this is taqwa! That you enact what Allah has commanded you, sincerely for Allah and in compliance to the Messenger of Allah (SAW), and that you leave what Allah has forbidden due to His prohibiting it and to steer clear of it.
For example that you establish the greatest obligation that Allah has imposed upon you after the testimony of faith – the prayer, and you establish it completely – fulfilling all of its conditions and pillars and obligations, fulfilling all of these perfectly. So whosoever leaves off any of these conditions, pillars or obligations then he has not feared Allah (to the best of his ability), rather he has been deficient in this to the extent of what he left out.
In Zakaah, the Taqwa of Allah lies in your calculating all of your property on which the zakat is due, and your giving the zakat as a means of purifying yourself without any miserliness or tightfistedness, or delay. And whosoever does not do this than he has not feared Allah.
In fasting, the Taqwa of Allah lies in your establishing the fast as you have been commanded, distancing yourself from idle speech, obscene words and mannerisms, boisterous behavior, backbiting and spreading tales and other such things that would make the fast deficient and remove the spirit of fasting. The true meaning of fasting is to fast from that which Allah, Azza wa Jall, has made forbidden. The same applies to all of the obligations that are used to establish obedience to Allah, and compliance to His command, sincerely for Him and in following His Messenger. Likewise all the forbidden actions are to be left in compliance to His prohibition.
THE SECOND: “and follow up and evil deed with a good one, it will efface it (the evil deed).”
Meaning that when you perform an evil action then follow it up with a good action for the good action effaces the evil. And from the good actions to be performed after the evil is that you repent to Allah for this evil action, for indeed repentance is from the most noble and excellent of the good actions as Allah has said, “indeed Allah Loves those who repent and those who purify themselves.” (2:222) And He said, “and repent to Allah all of you, O believers so that you may be successful.” (24:31)
Similarly righteous actions expiate the evil actions as the Prophet(SAW) said, “the five daily prayers and one Jumu’ah to the next Jumu’ah, and one Ramadan to the next Ramadan, is an expiation for what lies between them as long as one refrains from the major sins. [Muslim], and he said, “one Umrah to the next is an expiation for what is between them. [Bukhari].
Therefore the good actions efface the evil.
THE THIRD: “and deal with mankind with good manners.”
The first two pieces of advice were those related to relationship with the Creator, this third relates to relationship of the creation to the creation. This being to deal with mankind with the best manners such that you will be praised and not blamed. This by having a cheerful complexion, being truthful in speech, speaking to others nicely and other such good manners.
There are a large number of texts concerning the excellence of having good manners to the extent that the Messenger (SAW) said, “the most complete believer with respect to faith is the one with the best manners.” And he informed us that the most deserving of mankind to him (SAW) and the closest to him in ranking on the Day of Judgment would be those with the best manners.
So noble manners, along with their being a way to beautify gatherings and the person who possesses them being beloved to the people, contain a huge reward which will bestowed upon the person on the Day of Judgment.
So preserve these three pieces of advice from the Prophet (SAW) and Allah is the Grantor of Success.