Derek Prince clearly explains the ways of the Holy Spirit and how He works in the lives of Christians.

Through the power of the Holy Spirit, the believer can: experience the continual presence of Jesus; become a bold witness for Christ; acquire revelation of the Word of God; be led by the Spirit; Pray according to God's will; receive physical and emotional healing; understand the plans of God.

Power from the Holy Spirit is not limited to strength beyond the ordinary. That power also involves courage, boldness, confidence, insight, ability, and authority. The disciples would need all these gifts to fulfill their mission. If you believe in Jesus Christ as your Savior, you can experience the power of the Holy Spirit in your life.

Jesus promised the disciples that they would receive power to witness after they received the Holy Spirit. Notice the progression: (1) They would receive the Holy Spirit, (2) he would give them power, and (3) they would witness with extraordinary results. Often we try to reverse the order and witness by our own power and authority. Witnessing is not showing what we can do for God. It is showing and telling what God has done for us.