The fear of the LORD is the beginning of wisdom, and the knowledge of the Holy One is understanding (v10).
According to Luther, the natural man can not fear God perfectly. Holy fear is God given, enabling men to reverence God's authority, obey His commands and shun all forms of evil.
Holy fear is the beginning of wisdom, a feature of those whom God delights in (Ps147v11) and is the whole duty of man (Ec12v13).
Godly fear should stimulate us to seek holiness, for a day of judgment is coming (2Cor5v10). We are to fear the LORD, God's awesomeness has not changed.
Yet we must compliment this 'fear of the LORD' with Jesus' teaching on loving the Father with all our heart. We have been given the Spirit of sonship (Rom8v15) to help us in this.
Fear & love - a healthy and appropriate tension for those who love God.