"The fear of the Lord is the beginning of wisdom" (Ps 111:10). To effectively pray requires a reverance for God. This is achieved since his "'sheep follow Him because they know His voice'" (Jn 10:4). Jesus regularly went to solitary places to pray. You might say that way it was easier to hear God's "still small voice" (1Ki 19:12 KJV). How do his sheep learn God's voice? "Be still and know that I am God" (Ps 146:10). "He leads me beside quiet waters" (23:2). "I have stilled and quieted my soul" (131:2). Therefore "cease striving and know that I am God" (46:10). To be able to hear effectively we have to improve our hearing by "practice" (Heb 5:14) having our "senses trained" (:14). Through practice you protect against becoming "dull of hearing" (:11). Psalm 25 explains how God approaches this. He "leads the humble in justice, and He teaches the humble His way" (:9). "Who is the man who fears the Lord? He will instruct him in the way He should chose" (:12). "None of those who wait for You will be ashamed" (:3). "We do not know how to pray as we should, but the Spirit Himself intercedes for us . . . according to the will of God" (Ro 8:26-27).
The disciples received the Holy Spirit when Jesus breathed upon them (Jn 20:22). Then they were sealed (Eph 4:30) and received the promise of the Spirit in their hearts (2Co 1:22). Next Jesus said, "'Behold, I am sending forth the promise of My Father upon you: but you are to stay in the city until you are clothed with power from on high'" (Lk 24:49) for "'you will be baptized with the Holy Spirit not many days from now'" (Ac 1:5). Therefore, they received the "gift of the Holy Spirit" (2:38). "They were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit was giving them utterance" (:4). In another situation "while Peter was speaking these words, the Holy Spirit fell upon all those who were listening" (10:44) and "they were hearing them speaking with tongues" (:46) and Peter said it was "just as we did" (:47). Also, in Samaria they received the Spirit (:14-18) and Simon observed what he could "see and hear" (:33). Next, at Ephesus when "Paul had laid his hands upon them, the Holy Spirit came on them, and they began speaking with tongues and prophesying" (19:6). Paul said, "I thank God, I speak in tongues more than you all" (1Co 14:18). Then he said "I wish that you all spoke in tongues" (:5) and told them to "not forbid to speak in tongues" (:39). He explained "if I pray in a tongue, my spirit prays" (:14). If "we do not know how to pray as we should the Spirit Himself intercedes for us" (Ro 8:26). "One who speaks in a tongue does not speak to men but to God" (1Co 14:2). Consequently that person "edifies himself" (:4) and is established in the Spirit by "praying in the Holy Spirit" (Jude 20).