How can one definitively stop the practice of masturbation and the accompanying feelings of regret and guilt, while adhering to acts of worship and striving against one's desires? And is there a specific supplication to facilitate repentance and steadfastness upon it?

Masturbation and shaking hands with a non-mahram woman are forbidden. One must repent from these actions and not despair, while frequently supplicating with the prescribed prayers that suit the inquirer's situation, such as: "O Allah, I ask You for the performance of good deeds, the abandonment of evil deeds, and the love of the needy. And if You intend a trial for Your servants, then take me to You untempted," and "O Allah, I ask You for guidance, piety, chastity, and self-sufficiency," and "O Allah, purify my heart and protect my private parts," and "O Allah, I seek refuge in You from the evil of my hearing, and from the evil of my sight, and from the evil of my tongue, and from the evil of my heart, and from the evil of my semen."