Today we begin the Pentecost novena, nine days of prayer in preparation for the outpouring of the Holy Spirit on Pentecost Sunday. On this first day of the novena, Jesus tells us to ask for the Spirit in His name (Jn 16:23). Jesus says: "The heavenly Father [will] give the Holy Spirit to those who ask Him" (Lk 11:13).
We need these nine days to prepare us to ask rightly (see Jas 4:2-3). "We will receive at His hands whatever we ask" provided that "our consciences have nothing to charge us with" (1 Jn 3:22, 21). Thus, the Lord wants us to focus on repentance during this novena.
The disciples who prayed the first Pentecost novena "devoted themselves to constant prayer" (Acts 1:14). Prayer that is constant and communal works! They were filled with the Spirit on the day of Pentecost. Find some people to gather with to pray the novena.
Mary was central to the first Pentecost novena. Imagine how guilty the first disciples felt in abandoning Jesus during His crucifixion and thus adding to His pain. If you went to the funeral of someone you had hurt badly, imagine how comforted you'd feel to be loved and forgiven by the family of the deceased. Mary was Jesus' mother. Her presence with the disciples during the novena meant forgiveness and unity.
Repent and go to Confession. Pray with others. Pray with Mary. Receive the Holy Spirit!