Tauba:

To maintain their relationship with Allah (Subhanahu wa Ta’ala) it is necessary for all those who worship Allah (Subhanahu wa Ta’ala) to sincerely regret their sins and repent (perform Tauba) before Allah (Subhanahu wa Ta’ala). Hadhrat Muhaddith-e-Deccan (May Allah shower His Mercy on him) says about the importance and the conditions of repentance (Tauba):

Istighfaar is that you say Astaghfirullah (May Allah forgive me) with your tongue and regret with your heart and ask for forgiveness of Allah (Subhanahu wa Ta’ala).  This is not a difficult thing to do, is it? Maybe you think that now we will perform Tauba , what is the use if we commit a sin after that?  This is a whispering of Satan.  Repent with a sincere heart and decide firmly not to commit a sin.  Insha Allah, you will not commit a sin again.

Translation of Hadith: The one who repents from a sin is like the one who did not sin at all. (Sunan Ibn Majah, Kitab Uz Zuhd, Hadith No: 4240, Majma Uz Zawaaid, Vol. 10, Pg No: 200).

With repentance all the sins until now are forgiven.  Not only they are forgiven, but they are also wiped out from the records of deeds (naame a’amaal).  Being a human being, if you end up sinning again, repent again.

The worship done without Tauba is not waste, but worship after Tauba is a class apart.

Many people just say, Astaghfar what happens with that? Say the words mentioned in the Hadith: Astaghfirullahal Azeem Al Ladhi La Ilaha Illa Huwal Hayyul Qayyumu Wa Atubu Ilaih.

Learn this and if you are not able to remember, say: Astaghfirullah . This means: O Allah! I beg for Your forgiveness.

Daily, when you lie down on your bed, recite Istighfaar (any of the one given above) 3 times.  Due to this act, all the sins of the day are wiped out from the record of deeds even though they may be equal to the foam of the seas or the sand of the desert or like the leaves of the trees or like the number of days in the world.