What are the "correct" steps for a layman to be a Christian? Assume that I am a layman without knowledge other than science-related ones. How should I do to be a Christian in a correct way? 

In more strict words, what are the "correct" steps or algorithm to be a Christian? In more honest words, is assuming God(s) exist(s) the first step? You can also think of how do you persuade me to fear God, etc, etc.

I hope this question will be reopen to let others help me go to the heaven!
Yes, belief in God's existence is the first step. As Hebrews 11:6 says,


  And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him


Beyond that, the good news of the Gospel is that Jesus already has taken the first steps toward you becoming a Christian. 


  God is love. Whoever lives in love lives in God, and God in him. 17 In this way, love is made complete among us so that we will have confidence on the day of judgment, because in this world we are like him ... We love because he first loved us. 1 John 4:16-20


While the exact process of "conversion" is a matter of some debate, the sign that it has occurred is not - you are to grow in Christ, bearing fruit in keeping with repentance. As Paul says,


  But the Holy Spirit produces this kind of fruit in our lives: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. There is no law against these things! Those who belong to Christ Jesus have nailed the passions and desires of their sinful nature to his cross and crucified them there Galatians 5:24


Just remember, we obey out of love, not out of a need for love. As Jesus said,


  If you love me, you will obey what I command John 14:15


This is the way of the Gospel- that God loves us, and we in turn respond in obedience out of love, 


  For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— not by works, so that no one can boast. Ephesians 2:8-9




Or, if you prefer it all one text, consider Titus 3:3-8


  At one time we too were foolish, disobedient, deceived and enslaved by all kinds of passions and pleasures. We lived in malice and envy, being hated and hating one another.  But when the kindness and love of God our Savior appeared, he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit, whom he poured out on us generously through Jesus Christ our Savior, so that, having been justified by his grace, we might become heirs having the hope of eternal life. This is a trustworthy saying. And I want you to stress these things, so that those who have trusted in God may be careful to devote themselves to doing what is good. These things are excellent and profitable for everyone.