The day of Eid al-Ghadeer is the greatest Eid of Allah, the Eid of the Ahl al-Bayt (peace be upon them), and it is the greatest of Eids. It is known in the heavens as ‘The Day of the Famous Covenant’ and on earth as 'The Day of The Taken Solemn Covenant and Public Presence'.
The recommended acts of this great Eid are:
First: Observing fast on this day.
Second: Performing Ghusl (ritual bath)
Third: Reciting the Ziyarat of Amin Allah.
Fourth: Offering 2 rakaat prayer of Eid al-Ghadir before mid-day. In each Rakaat after Surat al-Fatiha recite 10 times Surat Ahad (Qul ho Allah ho Ahad), 10 times Surat al-Qadr and 10 times Ayat al-Kursi.
This prayer is highly rewarding and whatever dua is asked for from Allah, inshallah, will be granted. It is recommended to recite this prayer closer to but before mid-day since that was the time when Prophet Mohammad (Allah's prayers be upon him and upon his holy Household) announced the successorship and nomination of Imam Ali (peace be upon him) as master of the faithful.
After the prayers go into prostration and recite: 100 times "Shukran Lillah" and 100 times "Alhamd-o-lillah".
Imam Ja'far as-Sadeq (peace be upon him) says that whoever does so will be like a person who accepted the Imamate and Caliphate of Imam Ali (peace be upon him) and pledged allegiance at the Ghadeer Khum in front of Prophet Mohammad (Allah's prayers be upon him and upon his holy Household). The person who performs this act will also like those who will be with the Imam of Time and Order (peace be upon him) under his flag.
Sixth: Performing Ghusl and praying two rak'at prayer half hour before Dohr time, reciting in every Rak'at Surat al-Fatihah followed by Surat "Qol howa Allahu Ahad" ten times, ayat al-Kursi ten times and Surat al-Qadr ten times.
Seventh: Reciting Dua al-Nudba.
Eighth: Reading Dua narrated by Sayed Ibn Tawus from Sheikh al-Mufid.
Ninth: Congratulating the believers.
Tenth: Saying the following happy praises when meeting other believers: "اَلحمدُ لِلهِ الّذی جَعَلَنا مِنَ المُتَمَسّکینَ بِولایةِ اَمیرِالمؤمنینَ و الائمةِ المَعصومینَ علیهم السلام" ["Praise belongs to Allah, who made us among the adherers to the Wilaya of the Master of the Faithful (a) and the Infallible Imams (peace be upon them)"]
Among the acts of this Eid is Wearing nice clothes, Beautifying oneself, Wearing perfumes, Showing celebration, Forgiving the believers of the Shia of the Commander of the Faithful (Allah's prayers be upon him and upon his holy Household), Visiting Relatives, Giving food to believers, Offering Iftaar for the fasters, Greeting the believers and visiting them, Smiling at them, Sending them gifts, Thanking the Almighty God for His great bounty: the blessing of the Wilaya, Repeating the Salawat, Performing acts of worship and obedience, Giving Sadaqah, as a dirham given to the believing brother worth hundred thousand dirham in other days, and feeding the faithful in this day worth feeding all prophets and guardians.