Psalm 51

Remember the keys to repentance:
Acknowledge that God is God and you are not.
Acknowledge that you are sinful (name each specific sin).
Recognize that all sin is ultimately sin against God.
Understand that there is nothing for which you cannot repent.
Acknowledge that you cannot do anything to save yourself or remove your sin.
Believe that God is merciful and that he does forgive you for your sins.