Baptism
Dying in state of grace (no mortal sin)
Belief in divinely revealed doctrine. Available in the Bible or as summarized in the Catholic Catechism
http://www.usccb.org/beliefs-and-teachings/what-we-believe/catechism/catechism-of-the-catholic-church/index.cfm
Being a practicing member of the Body of Christ in the Church founded by Jesus.
Prayer and the Sacraments
Jesus' response to a question: What must a a man DO to be saved?
Jesus answered, The work of God is this: to believe in the one he has sent.
John 6:28-29
Pick one only...