Here, David invites young people to learn from him. Historically, students were referred to as sons or children. His lesson here is to understand what it means to "fear" God as well as the consequences of doing so. It is important to keep in mind that "fear" of God in a biblical context does not refer to dread but rather to respect and worship. A father is obligated by the Bible to teach his children about God and His ways.
During his lifetime, David was a man after God's own heart who sought to pass on the truths of the glorious goodness of God to the next generation. He invites us to taste and see the goodness of the Lord. Throughout this passage, we find that his song of praise gradually transforms into a practical instruction on the fear of the Lord and absorbing the truth from His Word.
Throughout his life, David made a number of foolish mistakes, but he was a man after God's own heart because he learned to rely on the Lord in all things and not to rely on His own understanding. Finally, David learned to acknowledge the Lord in everything, and he became a wise parent by teaching his children - and their children - that the fear of the Lord starts with wisdom and understanding.

Dear Heavenly Father, Your Psalms are full of truths and lessons that I can learn from them. Please allow me to teach my children to be respectful of You in all things. In every situation, may they learn how important it is to listen to Your voice and trust Your Word. My prayer for today's youth is to bring many to a saving faith and an appreciation for Your goodness and grace who do not have the godly counsel David provided to his sons. 
In Jesus's name I pray. Amen.