Firstly, if someone else can perform this duty better than yourself through better presentation of the issue, your duty is to let the others conduct that role.  When Allahﷻ ordered Prophet Moses peace be upon him, to go to Pharaoh to show him the right path, Prophet Moses peace be upon him, requested his brother Harun peace be upon him, who had a better ability to communicate, be sent along with him.

{وَأَخِى هَـٰرُونُ هُوَ أَفْصَحُ مِنِّى لِسَانًا فَأَرْسِلْهُ مَعِىَ}

“Moreover my brother Aaron is more eloquent than I. Send him with me as a helper”([1]).

Secondly, sometimes once is not enough, but rather multiple clarifications and different methods may be required for an effect to take place.  Just like hardened wood that won’t be cut with a single strike of an axe, but rather repeated strikes are required. The Qur’an says that

{وَلَقَدْ صَرَّفْنَا فِى هَـٰذَا ٱلْقُرْءَانِ لِيَذَّكَّرُوا}

We have explained (things) in various (ways) in this Qur’an, in order that they may receive admonition([2]).

Thirdly, it is possible that our methodology is incorrect and the reason for the lack of effect.  This is because “enjoining of good and prohibition of wrong” has conditions and principles applicable so that each wrong has to be approached in its own unique way.

Sometimes clothing is dirtied with dust, and other times it is dirtied with soot.  Dust can be slapped away but that same strike on soot on your clothes will not only dirty your hands with the same, but also drive the soot deeper in to the fabric of clothes.  Removal of soot is by blowing on it while dust is with hitting it and therefore dusting it away.   Each wrong requires its own methodology.

As the Qur’an states:

{وَأْتُوا ٱلْبُيُوتَ مِنْ أَبْوَٰبِهَا}

Enter houses through the proper doors([3]), meaning you should enter each house through its own entry path.

Fourthly, to stop people from doing wrong, you must use lawful approaches.  When Prophet Lot peace be upon him, saw his community wanting to approach his guests with evil intention, he opened lawful doors to them so as to prevent them from committing sin:

{قَالَ يَـٰقَوْمِ هَـٰٓؤُلَآءِ بَنَاتِى هُنَّ أَطْهَرُ لَكُمْ ۖفَٱتَّقُوا ٱللَّـهَ وَلَا تُخْزُونِ فِى ضَيْفِىٓ}

He said: “O my people! Here are my daughters: they are purer for you (if ye marry)! Now fear Allah, and cover me not with shame about my guests!([4])

[1] Al Qusas 28:34

[2] Israa 17:41

[3] Baqarah 2:189

[4] Hud 11:78