The basic idea is that this guy is a sinner and he knows it. He has seen the product of his own self-guidance and where it gets him. But he also fears the Lord and in humility knows that the LORD's ways are good and right. From this standpoint he has two great hopes. One is that the character and nature of God is such as to have mercy and forgive. The second is that God will not stop at a merely judicial forgiveness but is also such as to teach the sinner his very own ways. Because of this the Psalmist can hope in a deep inner transformation. He is not left to his own devices, but the very best Father and the very best Teacher will guide and instruct him until he becomes more like them.