As humans, we sin. Think of it in this way, God created us as humans, not Angels. By doing so, He already knew that we would be inclined to sin and do wrong deeds. We have been created as weak, which is why we need Allah's help and support. Allah is Al-Hayyi and Al-Qayyyum. Meaning, He is the One Who brings into existence and supports what He has created. We have been told in the Qur'an to seek help from Allah:

Thee alone do we worship and Thee alone do we implore for help. [1:5]

WHAT IS ISTIGHFAR?
The root of istighfar is ghafar, meaning to cover up. Istighfar means to get strength from Allah to refrain from sin and evil, and to be able to display this strength to refrain from sin. It helps to suppress any feelings or thoughts that may distance one from Allah.


SIN AND ISTIGHFAR
We should note that sin is not a prerequisite for Istighfar. As people, we wish to make Allah happy and in order to do so we want to become perfect beings. To achieve this perfection we ask Allah for strength. Even the Prophets needed Istighfar, so that no sin should be committed. Istighfar is also needed after an evil has been done. The Holy Prophet (peace be upon him) brought people who had completely gone astray to the highest point of civilization through Istighfar.

In the Holy Qur'an, Istighfar is seen as drawing the strength and support of Allah which leads to attaining nearness to Allah and salvation. The Holy Qur'an states:

But surely the righteous will be in the midst of gardens and springs, receiving what the Lord will give them; for they used to do good before that. They used to sleep but a little of the night; and at the dawn of the day they sought forgiveness...[51:16-19]

This verse shows that the one who does Istighfar is doing a righteous deed and is the recipient of countless blessings. Istighfar isn't to protect one from the torment of fire rather a part of goodness. For example, if one becomes a Mohsin he is at a stage where he is unable to sin. However, them doing Istighfar isn't necessarily to protect them from Hell, rather to get the necessary strength and support from Allah so that they stay firm on the right path and don't fall into the wrong path. Only because he knows that as a human, he can easily fall weak, and needs Allah's help.

DIFFERENCE BETWEEN ISTIGHFAR AND REPENTANCE
Istighfar and repentance are two separate things. The strength to repent comes after one does Istighfar. This is because, until we seek strength from Allah (through Istighfar) we are unable to do anything. It is with this strength that we can then stand up and express remorse about a wrongdoing or sin.

The Holy Prophet (peace be upon him) said:

If anyone continuously asks pardon, Allah will appoint for him a way out of every distress, and a relief from every anxiety, and will provide from him where he did not reckon [Abu Dawud]

HOW TO DO ISTIGHFAR

Continuously recite Astaghfirullah - "I seek forgiveness from Allah" to abstain from doing wrong such as envy, jealousy, pride etc.

Sayyad-ul-Istighfar (Best Prayer for Seeking Forgiveness)
Hadhrat Buraida relates the Holy Prophet (saw) said that whosoever recites this prayer morning or evening and dies on that day or that night he will enter heaven:


O Allah, You are my Lord, there is none worthy of worship except You. You created me and I am Your servant. And I am steadfast in Your convenant and Your promise to the best of my capability. I seek refuge in You from the evil effects of my deeds. I acknowledge Your blessings and favours. I confess my sins, so You forgive me, as there is none except You who forgives sins.

Prayer for Forgiveness and Pardon
Hadhrat Abu Musa-al-Ashari tells us of this prayer of the Holy Prophet (saw):


O Allah, forgive my mistakes, my lack of knowledge, my transgressions in my affairs and all my affairs about which know more than I do. Forgive my sins, my intentional or unintentional mistakes and my frivulous jokes. All these are my failings. O Allah, forgive my earlier or later sins. Forgive my hidden and manifest sins. You cause things to advamce and cause them to retard. You have authority over everything.

An Effective Prayer for Forgiveness



I seek forgiveness from Him, except Whom there is none worthy of worship. He is Living and Self-Subsisting. He brings others to life and sustains them. I incline towards Him and repent.

Basically, the one who resorts to Istighfar and admits his weakness to Allah becomes nearer to Him. When you continuously recur to Istighfar and turn to Allah for help, it allows you to resist evil tendencies with the help and strength given to you by Allah.