1 Samuel tells us much about what God had in mind when he instituted human leadership. Leadership is always to be leadership "under God," and not "under the leader." Saul led Israel for himself, while David led Israel for God. That was the difference. Leadership is a stewardship not an ownership.
As you read this book, also notice God's plan for David. He chose and anointed young David long before his reign would ever begin. He chose the most unassuming son of Jesse to become Israel's greatest king. He protected David through all of Saul's hatred and threats. To every Christian, God tells us we were chosen before the creation of the world (see Ephesians 1:4) and that every crash and turn in our life is under his watchful care (see Romans 8:28). David's unusual looking life is really a picture of ours, laid out for us to learn from.