It is advisable to stay awake during this full night in prayer as it has many rewards, hadith has confirmed that as for one who spends this whole night with acts of worship, his heart will not die when other hearts die.
Recite 100 times :
سُبْحَانَ اللّهِ وَالْحَمْدُ لِلّهِ وَلا إلهَ إلاَّ اللّه وَاللّهُ أَك ْبَرُ
Subh'aanallah Walh'amdu Lillah Wa-Laa Ilaaha Illallah Ho Wal Allahu Akbar
Perform Ghusl (Bath) with the thought of washing away sins and as if its your last Ghusl.
Recite 100 times 'Astaghfirullah' with attention to seeking forgiveness.
Recite Ziarat of Imam Husayn(as)
Recite Special Ziarat of Imam Husayn(as) for 15 Shaban as all the Prophets & Angels visit the Imam on this night.
As a short salutation ,one may go to the terrace/elevated place, look left, right & towards the sky & recite :- السَّلامُ عَلَيْكَ يَا أَبَا عَبْدِ اللّه السَّلامُ عَلَيْكَ وَرَحْمَةُ اللّه وَبَرَكَاتُهُ Assalamu Alalika Ya Aba Abdillah Assalamu Alaikum wa Rahmatullah e wabarakatoh Peace be upon you; O Aba-`Abdullah! Peace and Allah’s mercy and blessings be upon you.
Offer Namaz /Salaat of Jafar-e-Tayyar
Recite Dua Kumayl for Seeking forgiveness. In Hadith, it is mentioned that Kumayl ibn Ziyad said, "I was sitting with my master Amir al-Mominin ‘Ali ibn Abu Talib (peace be upon him) in Masjid Kufa and a group of companions were also sitting with him. One of them asked him what the meaning of the verse 'Whereupon every wise command is made clear.' (Surah ad-Dukhan, Verse 4) The Imam (peace be upon him) replied, The meaning of this is the night of the 15th of Sha‘ban. I swear by the One who holds the life of ‘Ali in His hands there is not a single servant of Allah except that all the good and bad that will reach him in this year is divided up and handed out on the 15th of Sha‘ban and this good and bad will continue from the 15th of Sha‘ban until the next year on the same night. The servant who stays up this night and recites the Du‘a of Khidr will have his supplications answered." This dua taught to Kumayl ibn Ziad is now known popularly as Dua e Kumayl.
Seek closeness to Imam al-Mehdi (may Allah hasten his return) the Hujjah of our Time; Wali al-‘Amr; the Greatest Secret (of Allah); the possessor of the divine Occultation and inviter to the message of the Prophet; the Successor of all Prophets and the Successor of all Successors of the Prophets; the physical manifestation of the Justice of Allah; the Flag of Guidance; the one who will destroy all corruption and oppression and those who oppose the truth; the destroyer of the enemies of Allah - the misguided and the disbelievers; the one who will purify the Earth of deviation and worship of the self; the greatest sign of Allah; the one who acts as the connection between the heavens and the earth; our Imam, Master and Qaim, al-Mahdi - may my soul and the souls of all of those in the universe be sacrificed for him.
Stay busy in Ziyarat, Munajat and asking our desires and complaining of our separation from our awaited Imam.
Write an Ariza(Letter)to Imam. Our supplications and Salat should always be performed with the thought in the back of our minds of the distance from our leader however we should also keep in mind and be thankful to Allah swt that we are blessed with such a guide. Recite the duas relating to the Imam (atfs) Dua Nudba , Isteghasa & Ziarat Aale Yasin of the Ahlulbayt(as).
It is recommended to mention Almighty Allah by the following invocation one hundred times so that one’s past acts of disobedience to Almighty Allah will be forgiven and one’s worldly and religious needs will be settled:
subhana allahi, All glory be to Allah;
walhamdu lillahi, all praise be to Allah;
وَلا إلهَ إلاَّ اللّهُ،
wa la ilaha illa allahu, there is no god save Allah;
wallahu akbaru, Allah is the Greatest;