For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
In answer on how to be a good Christian the following are necessary:
As Jesus said our first priority is to love God with all of our being and to love our neighbor [all men] as we love ourselves. The third is to seek first the Kingdom of God and this comes with a promise that if we do indeed seek first the Kingdom of God, He will provide for us all that we have need of. Notice I didn't say He will give all that we want, but what we have need of, what He know we need for our own good.
A mature Christian "preaches" with his or her life.
In 1 Corinthians 6:19 Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own; Hence, as a good Christian, we should be a good role model as Christ is our good role model. There is no good and bad Christian, because a Christian is a person who is having the qualities of Christ. Christianity is not a religion, it is the way of practical living among this cruel world.
The best way is to first make sure that you have obeyed the Gospel and have become an actual Christian, the way the Bible teaches.
What must I do to be saved?
Let us look at what the Apostles told everyone they must do to be saved,
Hear- Romans 10:17, Matthew 11:15, Acts 18:8, Acts 28:28.
Believe- John 5:24, Mark 16:16, Acts 16:31-33, Acts 18:8.
Confess- 1 John 4:15, Romans 10:9-10, Acts 8:35-38.
Repent- Luke 13:3, Acts 2:38, Acts 3:19, Matthew 9:13.
Baptized- John 3:5, Mark 16:16, Acts 2:38, Acts 8:5-13, Acts 8:35-38, Acts 9:17-19, Acts 10:47-48, Acts 16:13-15, Acts 16:31-33, Acts 18:8, Acts 22:16, Matthew 28:19.
Then God adds you into the Church- Acts 2:41, Acts 2:47, Colossians 2:12, Galatians 3:27, Romans 6:3-11.
Study the Scriptures daily- 2 Timothy 2:15.
Endure to the end- Matthew 24:13.