Firstly: 

It is not prescribed to place the hands over the face after finishing prayer or after finishing du’aa’. The best of guidance is the guidance of our Prophet Muhammad (peace and blessings of Allaah be upon him). When he said the salaam (at the end of prayer) he would pray for forgiveness three times, but he did not wipe his face with his hands after saying the salaam or after saying du’aa’. 

It was narrated that Thawbaan (may Allaah be pleased with him) said: When the Messenger of Allaah (peace and blessings of Allaah be upon him) had finished his prayer, he would pray for forgiveness three times, and say: “Allaahumma anta al-salaam wa minka al-salaam, tabaarakta yaa dhaa’l-jalaali wa’l-ikraam (O Allaah, You are al-Salaam (the One Who is free from all defects and deficiencies) and from You is all peace, blessed are You, Possessor of majesty and honour)”. Narrated by Muslim (591). 

In the answer to question no. 39174 we stated that it is not prescribed to wipe the face with the hands after saying du’aa’. 

Secondly: 

Shaking hands is something that is mentioned and encouraged in sharee’ah, and it is a cause of sins being forgiven. 

It was narrated that al-Bara’ ibn ‘Aazib (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “There are no two Muslims who meet and shake hands, but they will be forgiven before they part.” Narrated and classed as hasan by al-Tirmidhi (2727); narrated by Ibn Maajah (3703); classed as saheeh by al-Albaani in Saheeh al-Targheeb, 2718. 

Some people put their hands over their hearts after greeting and shaking hands with someone, but this is contrary to the meaning of shaking hands both in linguistic terms and in Islamic terminology. There is no evidence for that in the Sunnah, and there is no report – as far as we know – which says that any of the salaf did that. 

Shaking hands means clasping the palm of one hand against the palm of the other person’s hand. 

Al-Raaghhib al-Asfahaani said: 

Shaking hands means stretching the palms of the hands (against one another). 

Ghareeb al-Qur’aan (1/282). 

And Ibn Hajar al-‘Asqallaani said: 

Shaking hands means clasping the palm of one hand against the palm of the other hand. 

Fath al-Baari (11/54) 

Shaking hands is sufficient to greet a person in accordance with the Sunnah. However, if the people are accustomed to placing the hand over the heart after shaking hands or greeting someone as a way of showing honour to them, then we hope that there is nothing wrong with it, but we should not attribute that to the Sunnah of the Prophet (peace and blessings of Allaah be upon him), rather a person may do it on the basis that it is customary and not the Sunnah of the Prophet (peace and blessings of Allaah be upon him). 

And Allaah knows best.