Well, I give one example:
For years when I heard the story of David and Goliath I always heard it preached (and I read it as) David was a type of a true believer who trusts in His God and stands up to the enemies of God; as opposed to Saul who is "backslidden" and full of unbelief,and so on...
But, if we interpret the scripture as Jesus did, that the Old Testament spoke of Him. We see the King of Israel in David. The Annointed One (the Christ, Messaiah) chosen of God, coming down out of obscurity into the valley to defeat the enemies of God. He not only defeated the enemy for the Glory of God, but He saved the people of God. His victory was their victory, for he caused them, by His victory, to remain in the land...in their inheritance.
Thanks be to God who gives us the victory!
If we liken David to a faithful new testament believer...we rob ourselves of the Gospel... the power of God.