Resist the devil. James 4:7 says "Resist the devil, and he will flee from you." Prince gives seven steps to resist the devil.
James 4:7 NIV
Submit yourselves, then, to God. Resist the devil, and he will flee from you.
1. Establish a clear scriptural basis for resisting the devil. When Jesus was tempted by the devil He answered on the basis of scripture. The devil is a legalist as you resist the devil you need to be on solid scriptural ground. We resist the devil on the basis of what Jesus did on the Cross. The Cross is God's great stop sign. The devil can't go around the Cross, can't go over the Cross, can't go under the Cross, and can't go through the Cross. The Cross is God's great stop sign.
Christ became a curse that we might receive the blessing.
Galatians 3:13-14 NKJV
Christ has redeemed us from the curse of the law, having become a curse for us (for it is written, "Cursed is everyone who hangs on a tree"),  that the blessing of Abraham might come upon the Gentiles in Christ Jesus, that we might receive the promise of the Spirit through faith.
We have been redeemed through His blood. Our sins are forgiven, any legal claim the devil may have had on our life is fully paid, completely cancelled. And on the basis of what Jesus did on the Cross we can resist the devil.
Ephesians 1:7 NIV
In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God's grace
Colossians 1:12-14 NIV
and giving joyful thanks to the Father, who has qualified you to share in the inheritance of his holy people in the kingdom of light.  For he has rescued us from the dominion of darkness and brought us into the kingdom of the Son he loves,  in whom we have redemption, the forgiveness of sins.
1 John 3:8 NIV
The one who does what is sinful is of the devil, because the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the devil's work.
If the promise is that nothing will hurt you be assured something will try to hurt you. The enemy is always going to try to hurt you. But Jesus gives us the power to "overcome all the powers of the enemy."
Luke 10:19 NIV
I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy; nothing will harm you.
We need to be ever alert to the plans and schemes of the enemy.
1 Peter 5:8-9 NIV
Be alert and of sober mind. Your enemy the devil prowls around like a roaring lion looking for someone to devour.  Resist him, standing firm in the faith, because you know that the family of believers throughout the world is undergoing the same kind of sufferings.
2. Confess your faith in Christ. He is the High Priest of our confession. We need to say it out loud to add emphasis.
Hebrews 3:1 NKJV
Therefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our confession, Christ Jesus,
3. Commit yourself to obedience by the grace of God by the grace of God. Prince describes the great watershed of faith. Imagine the continental divide in the Rocky Mountains. Two rain drops fall on opposite sides of the divide, only inches apart. But they have completely different destinies thousands of miles apart. One ends up in the Pacific Ocean, the other in the Gulf of Mexico. You may be sitting only inches apart from someone and yet have completely different destinies. What is the great divide - obedience? Obedience will determine your destiny - blessings or curses.
Matthew 6:14-15 NIV
For if you forgive other people when they sin against you, your heavenly Father will also forgive you.  But if you do not forgive others their sins, your Father will not forgive your sins.