Repentance is not an easy matter. It is not achieved except by certain and practical conditions.
Among the elements that form the basic adobes in building the real repentance are regretting, determining to give up sin forever, changing one’s bad morals into good ones, repairing one’s deeds and past and relying on believing in Allah and the Day of Resurrection in following the straight path and the way of perfection.
Allah has said,
“Except those who repent and amend and make manifest (the truth), these it is to whom I turn (mercifully); and I am the Oft-returning (to mercy), the Merciful.” Qur'an, 2:160
“Repentance with Allah is only for those who do evil in ignorance, then turn (to Allah) soon, so these it is to whom Allah turns (mercifully), and Allah is ever Knowing, Wise.” Qur'an, 4:17
“But whoever repents after his iniquity and reforms (himself), then surely Allah will turn to him (mercifully); surely Allah is Forgiving, Merciful.” Qur'an, 5:39
“And (as to) those who do evil deeds, then repent after that and believe, your Lord after that is most surely Forgiving, Merciful.” Qur'an, 7:153
“But if they repent and keep up prayer and pay the poor-rate, they are your brethren in faith.” Qur'an, 9:11
According to these verses we notice that the conditions of the real repentance are: believing in Allah and the Day of Resurrection, reforming one’s faith, morals and doings, prompt turning (to Allah) without any delay, cutting one’s relation with injustice and sin, offering prayers, paying zakat and giving the rights of people back to them. Whoever repents in this way his repentance no doubt is a real repentance and then it will definitely be accepted by Allah.
source : REPENTANCE THE CRADLE OF MERCY By Husayn Ansariyan