Baptism is the first sacrament. Before Baptism, you can not accept any Sacrament.
Baptism is also the most-needed sacrament. For the one who does not receive the sacrament of baptism can not obtain salvation according to the words of the Lord Jesus: “If anyone is not born of water and the Holy Spirit, he can not enter the Kingdom of God” (Jn 3.5). The Catholic Church baptizes, obeying the Savior’s command: “Go and teach all nations, baptizing them in the Name of the Father and of the Son and of the Holy Spirit” (Mt 28, 19).
Video – Baptismal Preparation ( https://www.youtube.com/watch?v=2sPzH73sUsw )